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core/num/
f32.rs

1//! Constants for the `f32` single-precision floating point type.
2//!
3//! *[See also the `f32` primitive type][f32].*
4//!
5//! Mathematically significant numbers are provided in the `consts` sub-module.
6//!
7//! For the constants defined directly in this module
8//! (as distinct from those defined in the `consts` sub-module),
9//! new code should instead use the associated constants
10//! defined directly on the `f32` type.
11
12#![stable(feature = "rust1", since = "1.0.0")]
13
14use crate::convert::FloatToInt;
15use crate::num::FpCategory;
16use crate::panic::const_assert;
17use crate::{cfg_select, intrinsics, mem};
18
19/// The radix or base of the internal representation of `f32`.
20/// Use [`f32::RADIX`] instead.
21///
22/// # Examples
23///
24/// ```rust
25/// // deprecated way
26/// # #[allow(deprecated, deprecated_in_future)]
27/// let r = std::f32::RADIX;
28///
29/// // intended way
30/// let r = f32::RADIX;
31/// ```
32#[stable(feature = "rust1", since = "1.0.0")]
33#[deprecated(since = "TBD", note = "replaced by the `RADIX` associated constant on `f32`")]
34#[rustc_diagnostic_item = "f32_legacy_const_radix"]
35pub const RADIX: u32 = f32::RADIX;
36
37/// Number of significant digits in base 2.
38/// Use [`f32::MANTISSA_DIGITS`] instead.
39///
40/// # Examples
41///
42/// ```rust
43/// // deprecated way
44/// # #[allow(deprecated, deprecated_in_future)]
45/// let d = std::f32::MANTISSA_DIGITS;
46///
47/// // intended way
48/// let d = f32::MANTISSA_DIGITS;
49/// ```
50#[stable(feature = "rust1", since = "1.0.0")]
51#[deprecated(
52    since = "TBD",
53    note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
54)]
55#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
56pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
57
58/// Approximate number of significant digits in base 10.
59/// Use [`f32::DIGITS`] instead.
60///
61/// # Examples
62///
63/// ```rust
64/// // deprecated way
65/// # #[allow(deprecated, deprecated_in_future)]
66/// let d = std::f32::DIGITS;
67///
68/// // intended way
69/// let d = f32::DIGITS;
70/// ```
71#[stable(feature = "rust1", since = "1.0.0")]
72#[deprecated(since = "TBD", note = "replaced by the `DIGITS` associated constant on `f32`")]
73#[rustc_diagnostic_item = "f32_legacy_const_digits"]
74pub const DIGITS: u32 = f32::DIGITS;
75
76/// [Machine epsilon] value for `f32`.
77/// Use [`f32::EPSILON`] instead.
78///
79/// This is the difference between `1.0` and the next larger representable number.
80///
81/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
82///
83/// # Examples
84///
85/// ```rust
86/// // deprecated way
87/// # #[allow(deprecated, deprecated_in_future)]
88/// let e = std::f32::EPSILON;
89///
90/// // intended way
91/// let e = f32::EPSILON;
92/// ```
93#[stable(feature = "rust1", since = "1.0.0")]
94#[deprecated(since = "TBD", note = "replaced by the `EPSILON` associated constant on `f32`")]
95#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
96pub const EPSILON: f32 = f32::EPSILON;
97
98/// Smallest finite `f32` value.
99/// Use [`f32::MIN`] instead.
100///
101/// # Examples
102///
103/// ```rust
104/// // deprecated way
105/// # #[allow(deprecated, deprecated_in_future)]
106/// let min = std::f32::MIN;
107///
108/// // intended way
109/// let min = f32::MIN;
110/// ```
111#[stable(feature = "rust1", since = "1.0.0")]
112#[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on `f32`")]
113#[rustc_diagnostic_item = "f32_legacy_const_min"]
114pub const MIN: f32 = f32::MIN;
115
116/// Smallest positive normal `f32` value.
117/// Use [`f32::MIN_POSITIVE`] instead.
118///
119/// # Examples
120///
121/// ```rust
122/// // deprecated way
123/// # #[allow(deprecated, deprecated_in_future)]
124/// let min = std::f32::MIN_POSITIVE;
125///
126/// // intended way
127/// let min = f32::MIN_POSITIVE;
128/// ```
129#[stable(feature = "rust1", since = "1.0.0")]
130#[deprecated(since = "TBD", note = "replaced by the `MIN_POSITIVE` associated constant on `f32`")]
131#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
132pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
133
134/// Largest finite `f32` value.
135/// Use [`f32::MAX`] instead.
136///
137/// # Examples
138///
139/// ```rust
140/// // deprecated way
141/// # #[allow(deprecated, deprecated_in_future)]
142/// let max = std::f32::MAX;
143///
144/// // intended way
145/// let max = f32::MAX;
146/// ```
147#[stable(feature = "rust1", since = "1.0.0")]
148#[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on `f32`")]
149#[rustc_diagnostic_item = "f32_legacy_const_max"]
150pub const MAX: f32 = f32::MAX;
151
152/// One greater than the minimum possible normal power of 2 exponent.
153/// Use [`f32::MIN_EXP`] instead.
154///
155/// # Examples
156///
157/// ```rust
158/// // deprecated way
159/// # #[allow(deprecated, deprecated_in_future)]
160/// let min = std::f32::MIN_EXP;
161///
162/// // intended way
163/// let min = f32::MIN_EXP;
164/// ```
165#[stable(feature = "rust1", since = "1.0.0")]
166#[deprecated(since = "TBD", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
167#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
168pub const MIN_EXP: i32 = f32::MIN_EXP;
169
170/// Maximum possible power of 2 exponent.
171/// Use [`f32::MAX_EXP`] instead.
172///
173/// # Examples
174///
175/// ```rust
176/// // deprecated way
177/// # #[allow(deprecated, deprecated_in_future)]
178/// let max = std::f32::MAX_EXP;
179///
180/// // intended way
181/// let max = f32::MAX_EXP;
182/// ```
183#[stable(feature = "rust1", since = "1.0.0")]
184#[deprecated(since = "TBD", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
185#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
186pub const MAX_EXP: i32 = f32::MAX_EXP;
187
188/// Minimum possible normal power of 10 exponent.
189/// Use [`f32::MIN_10_EXP`] instead.
190///
191/// # Examples
192///
193/// ```rust
194/// // deprecated way
195/// # #[allow(deprecated, deprecated_in_future)]
196/// let min = std::f32::MIN_10_EXP;
197///
198/// // intended way
199/// let min = f32::MIN_10_EXP;
200/// ```
201#[stable(feature = "rust1", since = "1.0.0")]
202#[deprecated(since = "TBD", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
203#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
204pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
205
206/// Maximum possible power of 10 exponent.
207/// Use [`f32::MAX_10_EXP`] instead.
208///
209/// # Examples
210///
211/// ```rust
212/// // deprecated way
213/// # #[allow(deprecated, deprecated_in_future)]
214/// let max = std::f32::MAX_10_EXP;
215///
216/// // intended way
217/// let max = f32::MAX_10_EXP;
218/// ```
219#[stable(feature = "rust1", since = "1.0.0")]
220#[deprecated(since = "TBD", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
221#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
222pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
223
224/// Not a Number (NaN).
225/// Use [`f32::NAN`] instead.
226///
227/// # Examples
228///
229/// ```rust
230/// // deprecated way
231/// # #[allow(deprecated, deprecated_in_future)]
232/// let nan = std::f32::NAN;
233///
234/// // intended way
235/// let nan = f32::NAN;
236/// ```
237#[stable(feature = "rust1", since = "1.0.0")]
238#[deprecated(since = "TBD", note = "replaced by the `NAN` associated constant on `f32`")]
239#[rustc_diagnostic_item = "f32_legacy_const_nan"]
240pub const NAN: f32 = f32::NAN;
241
242/// Infinity (∞).
243/// Use [`f32::INFINITY`] instead.
244///
245/// # Examples
246///
247/// ```rust
248/// // deprecated way
249/// # #[allow(deprecated, deprecated_in_future)]
250/// let inf = std::f32::INFINITY;
251///
252/// // intended way
253/// let inf = f32::INFINITY;
254/// ```
255#[stable(feature = "rust1", since = "1.0.0")]
256#[deprecated(since = "TBD", note = "replaced by the `INFINITY` associated constant on `f32`")]
257#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
258pub const INFINITY: f32 = f32::INFINITY;
259
260/// Negative infinity (−∞).
261/// Use [`f32::NEG_INFINITY`] instead.
262///
263/// # Examples
264///
265/// ```rust
266/// // deprecated way
267/// # #[allow(deprecated, deprecated_in_future)]
268/// let ninf = std::f32::NEG_INFINITY;
269///
270/// // intended way
271/// let ninf = f32::NEG_INFINITY;
272/// ```
273#[stable(feature = "rust1", since = "1.0.0")]
274#[deprecated(since = "TBD", note = "replaced by the `NEG_INFINITY` associated constant on `f32`")]
275#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
276pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
277
278/// Basic mathematical constants.
279#[stable(feature = "rust1", since = "1.0.0")]
280#[rustc_diagnostic_item = "f32_consts_mod"]
281pub mod consts {
282    // FIXME: replace with mathematical constants from cmath.
283
284    /// Archimedes' constant (π)
285    #[stable(feature = "rust1", since = "1.0.0")]
286    pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
287
288    /// The full circle constant (τ)
289    ///
290    /// Equal to 2π.
291    #[stable(feature = "tau_constant", since = "1.47.0")]
292    pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
293
294    /// The golden ratio (φ)
295    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
296    pub const GOLDEN_RATIO: f32 = 1.618033988749894848204586834365638118_f32;
297
298    /// The Euler-Mascheroni constant (γ)
299    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
300    pub const EULER_GAMMA: f32 = 0.577215664901532860606512090082402431_f32;
301
302    /// π/2
303    #[stable(feature = "rust1", since = "1.0.0")]
304    pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
305
306    /// π/3
307    #[stable(feature = "rust1", since = "1.0.0")]
308    pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
309
310    /// π/4
311    #[stable(feature = "rust1", since = "1.0.0")]
312    pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
313
314    /// π/6
315    #[stable(feature = "rust1", since = "1.0.0")]
316    pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
317
318    /// π/8
319    #[stable(feature = "rust1", since = "1.0.0")]
320    pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
321
322    /// 1/π
323    #[stable(feature = "rust1", since = "1.0.0")]
324    pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
325
326    /// 1/sqrt(π)
327    #[unstable(feature = "more_float_constants", issue = "146939")]
328    pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
329
330    /// 1/sqrt(2π)
331    #[doc(alias = "FRAC_1_SQRT_TAU")]
332    #[unstable(feature = "more_float_constants", issue = "146939")]
333    pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
334
335    /// 2/π
336    #[stable(feature = "rust1", since = "1.0.0")]
337    pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
338
339    /// 2/sqrt(π)
340    #[stable(feature = "rust1", since = "1.0.0")]
341    pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
342
343    /// sqrt(2)
344    #[stable(feature = "rust1", since = "1.0.0")]
345    pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
346
347    /// 1/sqrt(2)
348    #[stable(feature = "rust1", since = "1.0.0")]
349    pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
350
351    /// sqrt(3)
352    #[unstable(feature = "more_float_constants", issue = "146939")]
353    pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
354
355    /// 1/sqrt(3)
356    #[unstable(feature = "more_float_constants", issue = "146939")]
357    pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
358
359    /// sqrt(5)
360    #[unstable(feature = "more_float_constants", issue = "146939")]
361    pub const SQRT_5: f32 = 2.23606797749978969640917366873127623_f32;
362
363    /// 1/sqrt(5)
364    #[unstable(feature = "more_float_constants", issue = "146939")]
365    pub const FRAC_1_SQRT_5: f32 = 0.44721359549995793928183473374625524_f32;
366
367    /// Euler's number (e)
368    #[stable(feature = "rust1", since = "1.0.0")]
369    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
370
371    /// log<sub>2</sub>(e)
372    #[stable(feature = "rust1", since = "1.0.0")]
373    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
374
375    /// log<sub>2</sub>(10)
376    #[stable(feature = "extra_log_consts", since = "1.43.0")]
377    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
378
379    /// log<sub>10</sub>(e)
380    #[stable(feature = "rust1", since = "1.0.0")]
381    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
382
383    /// log<sub>10</sub>(2)
384    #[stable(feature = "extra_log_consts", since = "1.43.0")]
385    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
386
387    /// ln(2)
388    #[stable(feature = "rust1", since = "1.0.0")]
389    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
390
391    /// ln(10)
392    #[stable(feature = "rust1", since = "1.0.0")]
393    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
394}
395
396#[doc(test(attr(allow(unused_features))))]
397impl f32 {
398    /// The radix or base of the internal representation of `f32`.
399    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
400    pub const RADIX: u32 = 2;
401
402    /// The size of this float type in bits.
403    #[unstable(feature = "float_bits_const", issue = "151073")]
404    pub const BITS: u32 = 32;
405
406    /// Number of significant digits in base 2.
407    ///
408    /// Note that the size of the mantissa in the bitwise representation is one
409    /// smaller than this since the leading 1 is not stored explicitly.
410    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
411    pub const MANTISSA_DIGITS: u32 = 24;
412
413    /// Approximate number of significant digits in base 10.
414    ///
415    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
416    /// significant digits can be converted to `f32` and back without loss.
417    ///
418    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
419    ///
420    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
421    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
422    pub const DIGITS: u32 = 6;
423
424    /// [Machine epsilon] value for `f32`.
425    ///
426    /// This is the difference between `1.0` and the next larger representable number.
427    ///
428    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
429    ///
430    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
431    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
432    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
433    #[rustc_diagnostic_item = "f32_epsilon"]
434    pub const EPSILON: f32 = 1.19209290e-07_f32;
435
436    /// Smallest finite `f32` value.
437    ///
438    /// Equal to &minus;[`MAX`].
439    ///
440    /// [`MAX`]: f32::MAX
441    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
442    pub const MIN: f32 = -3.40282347e+38_f32;
443    /// Smallest positive normal `f32` value.
444    ///
445    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
446    ///
447    /// [`MIN_EXP`]: f32::MIN_EXP
448    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
449    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
450    /// Largest finite `f32` value.
451    ///
452    /// Equal to
453    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
454    ///
455    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
456    /// [`MAX_EXP`]: f32::MAX_EXP
457    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
458    pub const MAX: f32 = 3.40282347e+38_f32;
459
460    /// One greater than the minimum possible *normal* power of 2 exponent
461    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
462    ///
463    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
464    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
465    /// In other words, all normal numbers representable by this type are
466    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
467    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
468    pub const MIN_EXP: i32 = -125;
469    /// One greater than the maximum possible power of 2 exponent
470    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
471    ///
472    /// This corresponds to the exact maximum possible power of 2 exponent
473    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
474    /// In other words, all numbers representable by this type are
475    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
476    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
477    pub const MAX_EXP: i32 = 128;
478
479    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
480    ///
481    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
482    ///
483    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
484    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
485    pub const MIN_10_EXP: i32 = -37;
486    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
487    ///
488    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
489    ///
490    /// [`MAX`]: f32::MAX
491    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
492    pub const MAX_10_EXP: i32 = 38;
493
494    /// Not a Number (NaN).
495    ///
496    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
497    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
498    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
499    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
500    /// info.
501    ///
502    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
503    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
504    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
505    /// The concrete bit pattern may change across Rust versions and target platforms.
506    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
507    #[rustc_diagnostic_item = "f32_nan"]
508    #[allow(clippy::eq_op)]
509    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
510    /// Infinity (∞).
511    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
512    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
513    /// Negative infinity (−∞).
514    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
515    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
516
517    /// Maximum integer that can be represented exactly in an [`f32`] value,
518    /// with no other integer converting to the same floating point value.
519    ///
520    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
521    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
522    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
523    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
524    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
525    /// "one-to-one" mapping.
526    ///
527    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
528    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
529    /// ```
530    /// #![feature(float_exact_integer_constants)]
531    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
532    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
533    /// let max_exact_int = f32::MAX_EXACT_INTEGER;
534    /// assert_eq!(max_exact_int, max_exact_int as f32 as i32);
535    /// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f32 as i32);
536    /// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f32 as i32);
537    ///
538    /// // Beyond `f32::MAX_EXACT_INTEGER`, multiple integers can map to one float value
539    /// assert_eq!((max_exact_int + 1) as f32, (max_exact_int + 2) as f32);
540    /// # }
541    /// ```
542    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
543    pub const MAX_EXACT_INTEGER: i32 = (1 << Self::MANTISSA_DIGITS) - 1;
544
545    /// Minimum integer that can be represented exactly in an [`f32`] value,
546    /// with no other integer converting to the same floating point value.
547    ///
548    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
549    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
550    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
551    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
552    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
553    /// "one-to-one" mapping.
554    ///
555    /// This constant is equivalent to `-MAX_EXACT_INTEGER`.
556    ///
557    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
558    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
559    /// ```
560    /// #![feature(float_exact_integer_constants)]
561    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
562    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
563    /// let min_exact_int = f32::MIN_EXACT_INTEGER;
564    /// assert_eq!(min_exact_int, min_exact_int as f32 as i32);
565    /// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f32 as i32);
566    /// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f32 as i32);
567    ///
568    /// // Below `f32::MIN_EXACT_INTEGER`, multiple integers can map to one float value
569    /// assert_eq!((min_exact_int - 1) as f32, (min_exact_int - 2) as f32);
570    /// # }
571    /// ```
572    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
573    pub const MIN_EXACT_INTEGER: i32 = -Self::MAX_EXACT_INTEGER;
574
575    /// The mask of the bit used to encode the sign of an [`f32`].
576    ///
577    /// This bit is set when the sign is negative and unset when the sign is
578    /// positive.
579    /// If you only need to check whether a value is positive or negative,
580    /// [`is_sign_positive`] or [`is_sign_negative`] can be used.
581    ///
582    /// [`is_sign_positive`]: f32::is_sign_positive
583    /// [`is_sign_negative`]: f32::is_sign_negative
584    /// ```rust
585    /// #![feature(float_masks)]
586    /// let sign_mask = f32::SIGN_MASK;
587    /// let a = 1.6552f32;
588    /// let a_bits = a.to_bits();
589    ///
590    /// assert_eq!(a_bits & sign_mask, 0x0);
591    /// assert_eq!(f32::from_bits(a_bits ^ sign_mask), -a);
592    /// assert_eq!(sign_mask, (-0.0f32).to_bits());
593    /// ```
594    #[unstable(feature = "float_masks", issue = "154064")]
595    pub const SIGN_MASK: u32 = 0x8000_0000;
596
597    /// The mask of the bits used to encode the exponent of an [`f32`].
598    ///
599    /// Note that the exponent is stored as a biased value, with a bias of 127 for `f32`.
600    ///
601    /// ```rust
602    /// #![feature(float_masks)]
603    /// fn get_exp(a: f32) -> i32 {
604    ///     let bias = 127;
605    ///     let biased = a.to_bits() & f32::EXPONENT_MASK;
606    ///     (biased >> (f32::MANTISSA_DIGITS - 1)).cast_signed() - bias
607    /// }
608    ///
609    /// assert_eq!(get_exp(0.5), -1);
610    /// assert_eq!(get_exp(1.0), 0);
611    /// assert_eq!(get_exp(2.0), 1);
612    /// assert_eq!(get_exp(4.0), 2);
613    /// ```
614    #[unstable(feature = "float_masks", issue = "154064")]
615    pub const EXPONENT_MASK: u32 = 0x7f80_0000;
616
617    /// The mask of the bits used to encode the mantissa of an [`f32`].
618    ///
619    /// ```rust
620    /// #![feature(float_masks)]
621    /// let mantissa_mask = f32::MANTISSA_MASK;
622    ///
623    /// assert_eq!(0f32.to_bits() & mantissa_mask, 0x0);
624    /// assert_eq!(1f32.to_bits() & mantissa_mask, 0x0);
625    ///
626    /// // multiplying a finite value by a power of 2 doesn't change its mantissa
627    /// // unless the result or initial value is not normal.
628    /// let a = 1.6552f32;
629    /// let b = 4.0 * a;
630    /// assert_eq!(a.to_bits() & mantissa_mask, b.to_bits() & mantissa_mask);
631    ///
632    /// // The maximum and minimum values have a saturated significand
633    /// assert_eq!(f32::MAX.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
634    /// assert_eq!(f32::MIN.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
635    /// ```
636    #[unstable(feature = "float_masks", issue = "154064")]
637    pub const MANTISSA_MASK: u32 = 0x007f_ffff;
638
639    /// Minimum representable positive value (min subnormal)
640    const TINY_BITS: u32 = 0x1;
641
642    /// Minimum representable negative value (min negative subnormal)
643    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
644
645    /// Returns `true` if this value is NaN.
646    ///
647    /// ```
648    /// let nan = f32::NAN;
649    /// let f = 7.0_f32;
650    ///
651    /// assert!(nan.is_nan());
652    /// assert!(!f.is_nan());
653    /// ```
654    #[must_use]
655    #[stable(feature = "rust1", since = "1.0.0")]
656    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
657    #[inline]
658    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
659    pub const fn is_nan(self) -> bool {
660        self != self
661    }
662
663    /// Returns `true` if this value is positive infinity or negative infinity, and
664    /// `false` otherwise.
665    ///
666    /// ```
667    /// let f = 7.0f32;
668    /// let inf = f32::INFINITY;
669    /// let neg_inf = f32::NEG_INFINITY;
670    /// let nan = f32::NAN;
671    ///
672    /// assert!(!f.is_infinite());
673    /// assert!(!nan.is_infinite());
674    ///
675    /// assert!(inf.is_infinite());
676    /// assert!(neg_inf.is_infinite());
677    /// ```
678    #[must_use]
679    #[stable(feature = "rust1", since = "1.0.0")]
680    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
681    #[inline]
682    pub const fn is_infinite(self) -> bool {
683        // Getting clever with transmutation can result in incorrect answers on some FPUs
684        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
685        // See https://github.com/rust-lang/rust/issues/72327
686        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
687    }
688
689    /// Returns `true` if this number is neither infinite nor NaN.
690    ///
691    /// ```
692    /// let f = 7.0f32;
693    /// let inf = f32::INFINITY;
694    /// let neg_inf = f32::NEG_INFINITY;
695    /// let nan = f32::NAN;
696    ///
697    /// assert!(f.is_finite());
698    ///
699    /// assert!(!nan.is_finite());
700    /// assert!(!inf.is_finite());
701    /// assert!(!neg_inf.is_finite());
702    /// ```
703    #[must_use]
704    #[stable(feature = "rust1", since = "1.0.0")]
705    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
706    #[inline]
707    pub const fn is_finite(self) -> bool {
708        // There's no need to handle NaN separately: if self is NaN,
709        // the comparison is not true, exactly as desired.
710        self.abs() < Self::INFINITY
711    }
712
713    /// Returns `true` if the number is [subnormal].
714    ///
715    /// ```
716    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
717    /// let max = f32::MAX;
718    /// let lower_than_min = 1.0e-40_f32;
719    /// let zero = 0.0_f32;
720    ///
721    /// assert!(!min.is_subnormal());
722    /// assert!(!max.is_subnormal());
723    ///
724    /// assert!(!zero.is_subnormal());
725    /// assert!(!f32::NAN.is_subnormal());
726    /// assert!(!f32::INFINITY.is_subnormal());
727    /// // Values between `0` and `min` are Subnormal.
728    /// assert!(lower_than_min.is_subnormal());
729    /// ```
730    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
731    #[must_use]
732    #[stable(feature = "is_subnormal", since = "1.53.0")]
733    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
734    #[inline]
735    pub const fn is_subnormal(self) -> bool {
736        matches!(self.classify(), FpCategory::Subnormal)
737    }
738
739    /// Returns `true` if the number is neither zero, infinite,
740    /// [subnormal], or NaN.
741    ///
742    /// ```
743    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
744    /// let max = f32::MAX;
745    /// let lower_than_min = 1.0e-40_f32;
746    /// let zero = 0.0_f32;
747    ///
748    /// assert!(min.is_normal());
749    /// assert!(max.is_normal());
750    ///
751    /// assert!(!zero.is_normal());
752    /// assert!(!f32::NAN.is_normal());
753    /// assert!(!f32::INFINITY.is_normal());
754    /// // Values between `0` and `min` are Subnormal.
755    /// assert!(!lower_than_min.is_normal());
756    /// ```
757    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
758    #[must_use]
759    #[stable(feature = "rust1", since = "1.0.0")]
760    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
761    #[inline]
762    pub const fn is_normal(self) -> bool {
763        matches!(self.classify(), FpCategory::Normal)
764    }
765
766    /// Returns the floating point category of the number. If only one property
767    /// is going to be tested, it is generally faster to use the specific
768    /// predicate instead.
769    ///
770    /// ```
771    /// use std::num::FpCategory;
772    ///
773    /// let num = 12.4_f32;
774    /// let inf = f32::INFINITY;
775    ///
776    /// assert_eq!(num.classify(), FpCategory::Normal);
777    /// assert_eq!(inf.classify(), FpCategory::Infinite);
778    /// ```
779    #[stable(feature = "rust1", since = "1.0.0")]
780    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
781    #[must_use]
782    pub const fn classify(self) -> FpCategory {
783        // We used to have complicated logic here that avoids the simple bit-based tests to work
784        // around buggy codegen for x87 targets (see
785        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
786        // of our tests is able to find any difference between the complicated and the naive
787        // version, so now we are back to the naive version.
788        let b = self.to_bits();
789        match (b & Self::MANTISSA_MASK, b & Self::EXPONENT_MASK) {
790            (0, Self::EXPONENT_MASK) => FpCategory::Infinite,
791            (_, Self::EXPONENT_MASK) => FpCategory::Nan,
792            (0, 0) => FpCategory::Zero,
793            (_, 0) => FpCategory::Subnormal,
794            _ => FpCategory::Normal,
795        }
796    }
797
798    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
799    /// positive sign bit and positive infinity.
800    ///
801    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
802    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
803    /// conserved over arithmetic operations, the result of `is_sign_positive` on
804    /// a NaN might produce an unexpected or non-portable result. See the [specification
805    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
806    /// if you need fully portable behavior (will return `false` for all NaNs).
807    ///
808    /// ```
809    /// let f = 7.0_f32;
810    /// let g = -7.0_f32;
811    ///
812    /// assert!(f.is_sign_positive());
813    /// assert!(!g.is_sign_positive());
814    /// ```
815    #[must_use]
816    #[stable(feature = "rust1", since = "1.0.0")]
817    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
818    #[inline]
819    pub const fn is_sign_positive(self) -> bool {
820        !self.is_sign_negative()
821    }
822
823    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
824    /// negative sign bit and negative infinity.
825    ///
826    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
827    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
828    /// conserved over arithmetic operations, the result of `is_sign_negative` on
829    /// a NaN might produce an unexpected or non-portable result. See the [specification
830    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
831    /// if you need fully portable behavior (will return `false` for all NaNs).
832    ///
833    /// ```
834    /// let f = 7.0f32;
835    /// let g = -7.0f32;
836    ///
837    /// assert!(!f.is_sign_negative());
838    /// assert!(g.is_sign_negative());
839    /// ```
840    #[must_use]
841    #[stable(feature = "rust1", since = "1.0.0")]
842    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
843    #[inline]
844    pub const fn is_sign_negative(self) -> bool {
845        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
846        // applies to zeros and NaNs as well.
847        self.to_bits() & 0x8000_0000 != 0
848    }
849
850    /// Returns the least number greater than `self`.
851    ///
852    /// Let `TINY` be the smallest representable positive `f32`. Then,
853    ///  - if `self.is_nan()`, this returns `self`;
854    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
855    ///  - if `self` is `-TINY`, this returns -0.0;
856    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
857    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
858    ///  - otherwise the unique least value greater than `self` is returned.
859    ///
860    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
861    /// is finite `x == x.next_up().next_down()` also holds.
862    ///
863    /// ```rust
864    /// // f32::EPSILON is the difference between 1.0 and the next number up.
865    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
866    /// // But not for most numbers.
867    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
868    /// assert_eq!(16777216f32.next_up(), 16777218.0);
869    /// ```
870    ///
871    /// This operation corresponds to IEEE-754 `nextUp`.
872    ///
873    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
874    /// [`INFINITY`]: Self::INFINITY
875    /// [`MIN`]: Self::MIN
876    /// [`MAX`]: Self::MAX
877    #[inline]
878    #[doc(alias = "nextUp")]
879    #[stable(feature = "float_next_up_down", since = "1.86.0")]
880    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
881    #[must_use = "method returns a new number and does not mutate the original value"]
882    pub const fn next_up(self) -> Self {
883        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
884        // denormals to zero. This is in general unsound and unsupported, but here
885        // we do our best to still produce the correct result on such targets.
886        let bits = self.to_bits();
887        if self.is_nan() || bits == Self::INFINITY.to_bits() {
888            return self;
889        }
890
891        let abs = bits & !Self::SIGN_MASK;
892        let next_bits = if abs == 0 {
893            Self::TINY_BITS
894        } else if bits == abs {
895            bits + 1
896        } else {
897            bits - 1
898        };
899        Self::from_bits(next_bits)
900    }
901
902    /// Returns the greatest number less than `self`.
903    ///
904    /// Let `TINY` be the smallest representable positive `f32`. Then,
905    ///  - if `self.is_nan()`, this returns `self`;
906    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
907    ///  - if `self` is `TINY`, this returns 0.0;
908    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
909    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
910    ///  - otherwise the unique greatest value less than `self` is returned.
911    ///
912    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
913    /// is finite `x == x.next_down().next_up()` also holds.
914    ///
915    /// ```rust
916    /// let x = 1.0f32;
917    /// // Clamp value into range [0, 1).
918    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
919    /// assert!(clamped < 1.0);
920    /// assert_eq!(clamped.next_up(), 1.0);
921    /// ```
922    ///
923    /// This operation corresponds to IEEE-754 `nextDown`.
924    ///
925    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
926    /// [`INFINITY`]: Self::INFINITY
927    /// [`MIN`]: Self::MIN
928    /// [`MAX`]: Self::MAX
929    #[inline]
930    #[doc(alias = "nextDown")]
931    #[stable(feature = "float_next_up_down", since = "1.86.0")]
932    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
933    #[must_use = "method returns a new number and does not mutate the original value"]
934    pub const fn next_down(self) -> Self {
935        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
936        // denormals to zero. This is in general unsound and unsupported, but here
937        // we do our best to still produce the correct result on such targets.
938        let bits = self.to_bits();
939        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
940            return self;
941        }
942
943        let abs = bits & !Self::SIGN_MASK;
944        let next_bits = if abs == 0 {
945            Self::NEG_TINY_BITS
946        } else if bits == abs {
947            bits - 1
948        } else {
949            bits + 1
950        };
951        Self::from_bits(next_bits)
952    }
953
954    /// Takes the reciprocal (inverse) of a number, `1/x`.
955    ///
956    /// ```
957    /// let x = 2.0_f32;
958    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
959    ///
960    /// assert!(abs_difference <= f32::EPSILON);
961    /// ```
962    #[must_use = "this returns the result of the operation, without modifying the original"]
963    #[stable(feature = "rust1", since = "1.0.0")]
964    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
965    #[inline]
966    pub const fn recip(self) -> f32 {
967        1.0 / self
968    }
969
970    /// Converts radians to degrees.
971    ///
972    /// # Unspecified precision
973    ///
974    /// The precision of this function is non-deterministic. This means it varies by platform,
975    /// Rust version, and can even differ within the same execution from one invocation to the next.
976    ///
977    /// # Examples
978    ///
979    /// ```
980    /// let angle = std::f32::consts::PI;
981    ///
982    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
983    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
984    /// assert!(abs_difference <= f32::EPSILON);
985    /// ```
986    #[must_use = "this returns the result of the operation, \
987                  without modifying the original"]
988    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
989    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
990    #[inline]
991    pub const fn to_degrees(self) -> f32 {
992        // Use a literal to avoid double rounding, consts::PI is already rounded,
993        // and dividing would round again.
994        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
995        self * PIS_IN_180
996    }
997
998    /// Converts degrees to radians.
999    ///
1000    /// # Unspecified precision
1001    ///
1002    /// The precision of this function is non-deterministic. This means it varies by platform,
1003    /// Rust version, and can even differ within the same execution from one invocation to the next.
1004    ///
1005    /// # Examples
1006    ///
1007    /// ```
1008    /// let angle = 180.0f32;
1009    ///
1010    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
1011    ///
1012    /// assert!(abs_difference <= f32::EPSILON);
1013    /// ```
1014    #[must_use = "this returns the result of the operation, \
1015                  without modifying the original"]
1016    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
1017    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1018    #[inline]
1019    pub const fn to_radians(self) -> f32 {
1020        // The division here is correctly rounded with respect to the true value of π/180.
1021        // Although π is irrational and already rounded, the double rounding happens
1022        // to produce correct result for f32.
1023        const RADS_PER_DEG: f32 = consts::PI / 180.0;
1024        self * RADS_PER_DEG
1025    }
1026
1027    /// Returns the maximum of the two numbers, ignoring NaN.
1028    ///
1029    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1030    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1031    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1032    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1033    /// non-deterministically.
1034    ///
1035    /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
1036    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1037    /// follows the IEEE 754-2008 semantics for `maxNum`.
1038    ///
1039    /// ```
1040    /// let x = 1.0f32;
1041    /// let y = 2.0f32;
1042    ///
1043    /// assert_eq!(x.max(y), y);
1044    /// assert_eq!(x.max(f32::NAN), x);
1045    /// ```
1046    #[must_use = "this returns the result of the comparison, without modifying either input"]
1047    #[stable(feature = "rust1", since = "1.0.0")]
1048    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1049    #[inline]
1050    pub const fn max(self, other: f32) -> f32 {
1051        intrinsics::maximum_number_nsz_f32(self, other)
1052    }
1053
1054    /// Returns the minimum of the two numbers, ignoring NaN.
1055    ///
1056    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1057    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1058    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1059    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1060    /// non-deterministically.
1061    ///
1062    /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
1063    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1064    /// follows the IEEE 754-2008 semantics for `minNum`.
1065    ///
1066    /// ```
1067    /// let x = 1.0f32;
1068    /// let y = 2.0f32;
1069    ///
1070    /// assert_eq!(x.min(y), x);
1071    /// assert_eq!(x.min(f32::NAN), x);
1072    /// ```
1073    #[must_use = "this returns the result of the comparison, without modifying either input"]
1074    #[stable(feature = "rust1", since = "1.0.0")]
1075    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1076    #[inline]
1077    pub const fn min(self, other: f32) -> f32 {
1078        intrinsics::minimum_number_nsz_f32(self, other)
1079    }
1080
1081    /// Returns the maximum of the two numbers, propagating NaN.
1082    ///
1083    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1084    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1085    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1086    /// non-NaN inputs.
1087    ///
1088    /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
1089    /// and which does not reliably order `-0.0` and `+0.0`.
1090    ///
1091    /// This follows the IEEE 754-2019 semantics for `maximum`.
1092    ///
1093    /// ```
1094    /// #![feature(float_minimum_maximum)]
1095    /// let x = 1.0f32;
1096    /// let y = 2.0f32;
1097    ///
1098    /// assert_eq!(x.maximum(y), y);
1099    /// assert!(x.maximum(f32::NAN).is_nan());
1100    /// ```
1101    #[must_use = "this returns the result of the comparison, without modifying either input"]
1102    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1103    #[inline]
1104    pub const fn maximum(self, other: f32) -> f32 {
1105        intrinsics::maximumf32(self, other)
1106    }
1107
1108    /// Returns the minimum of the two numbers, propagating NaN.
1109    ///
1110    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1111    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1112    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1113    /// non-NaN inputs.
1114    ///
1115    /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1116    /// and which does not reliably order `-0.0` and `+0.0`.
1117    ///
1118    /// This follows the IEEE 754-2019 semantics for `minimum`.
1119    ///
1120    /// ```
1121    /// #![feature(float_minimum_maximum)]
1122    /// let x = 1.0f32;
1123    /// let y = 2.0f32;
1124    ///
1125    /// assert_eq!(x.minimum(y), x);
1126    /// assert!(x.minimum(f32::NAN).is_nan());
1127    /// ```
1128    #[must_use = "this returns the result of the comparison, without modifying either input"]
1129    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1130    #[inline]
1131    pub const fn minimum(self, other: f32) -> f32 {
1132        intrinsics::minimumf32(self, other)
1133    }
1134
1135    /// Calculates the midpoint (average) between `self` and `rhs`.
1136    ///
1137    /// This returns NaN when *either* argument is NaN or if a combination of
1138    /// +inf and -inf is provided as arguments.
1139    ///
1140    /// # Examples
1141    ///
1142    /// ```
1143    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1144    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1145    /// ```
1146    #[inline]
1147    #[doc(alias = "average")]
1148    #[stable(feature = "num_midpoint", since = "1.85.0")]
1149    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1150    #[must_use = "this returns the result of the operation, \
1151                  without modifying the original"]
1152    pub const fn midpoint(self, other: f32) -> f32 {
1153        cfg_select! {
1154            // Allow faster implementation that have known good 64-bit float
1155            // implementations. Falling back to the branchy code on targets that don't
1156            // have 64-bit hardware floats or buggy implementations.
1157            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1158            any(
1159                target_arch = "x86_64",
1160                target_arch = "aarch64",
1161                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1162                all(target_arch = "loongarch64", target_feature = "d"),
1163                all(target_arch = "arm", target_feature = "vfp2"),
1164                target_arch = "wasm32",
1165                target_arch = "wasm64",
1166            ) => {
1167                ((self as f64 + other as f64) / 2.0) as f32
1168            }
1169            _ => {
1170                const HI: f32 = f32::MAX / 2.;
1171
1172                let (a, b) = (self, other);
1173                let abs_a = a.abs();
1174                let abs_b = b.abs();
1175
1176                if abs_a <= HI && abs_b <= HI {
1177                    // Overflow is impossible
1178                    (a + b) / 2.
1179                } else {
1180                    (a / 2.) + (b / 2.)
1181                }
1182            }
1183        }
1184    }
1185
1186    /// Rounds toward zero and converts to any primitive integer type,
1187    /// assuming that the value is finite and fits in that type.
1188    ///
1189    /// ```
1190    /// let value = 4.6_f32;
1191    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1192    /// assert_eq!(rounded, 4);
1193    ///
1194    /// let value = -128.9_f32;
1195    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1196    /// assert_eq!(rounded, i8::MIN);
1197    /// ```
1198    ///
1199    /// # Safety
1200    ///
1201    /// The value must:
1202    ///
1203    /// * Not be `NaN`
1204    /// * Not be infinite
1205    /// * Be representable in the return type `Int`, after truncating off its fractional part
1206    #[must_use = "this returns the result of the operation, \
1207                  without modifying the original"]
1208    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1209    #[inline]
1210    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1211    where
1212        Self: FloatToInt<Int>,
1213    {
1214        // SAFETY: the caller must uphold the safety contract for
1215        // `FloatToInt::to_int_unchecked`.
1216        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1217    }
1218
1219    /// Raw transmutation to `u32`.
1220    ///
1221    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1222    ///
1223    /// See [`from_bits`](Self::from_bits) for some discussion of the
1224    /// portability of this operation (there are almost no issues).
1225    ///
1226    /// Note that this function is distinct from `as` casting, which attempts to
1227    /// preserve the *numeric* value, and not the bitwise value.
1228    ///
1229    /// # Examples
1230    ///
1231    /// ```
1232    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1233    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1234    ///
1235    /// ```
1236    #[must_use = "this returns the result of the operation, \
1237                  without modifying the original"]
1238    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1239    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1240    #[inline]
1241    #[allow(unnecessary_transmutes)]
1242    pub const fn to_bits(self) -> u32 {
1243        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1244        unsafe { mem::transmute(self) }
1245    }
1246
1247    /// Raw transmutation from `u32`.
1248    ///
1249    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1250    /// It turns out this is incredibly portable, for two reasons:
1251    ///
1252    /// * Floats and Ints have the same endianness on all supported platforms.
1253    /// * IEEE 754 very precisely specifies the bit layout of floats.
1254    ///
1255    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1256    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1257    /// (notably x86 and ARM) picked the interpretation that was ultimately
1258    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1259    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1260    ///
1261    /// Rather than trying to preserve signaling-ness cross-platform, this
1262    /// implementation favors preserving the exact bits. This means that
1263    /// any payloads encoded in NaNs will be preserved even if the result of
1264    /// this method is sent over the network from an x86 machine to a MIPS one.
1265    ///
1266    /// If the results of this method are only manipulated by the same
1267    /// architecture that produced them, then there is no portability concern.
1268    ///
1269    /// If the input isn't NaN, then there is no portability concern.
1270    ///
1271    /// If you don't care about signalingness (very likely), then there is no
1272    /// portability concern.
1273    ///
1274    /// Note that this function is distinct from `as` casting, which attempts to
1275    /// preserve the *numeric* value, and not the bitwise value.
1276    ///
1277    /// # Examples
1278    ///
1279    /// ```
1280    /// let v = f32::from_bits(0x41480000);
1281    /// assert_eq!(v, 12.5);
1282    /// ```
1283    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1284    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1285    #[must_use]
1286    #[inline]
1287    #[allow(unnecessary_transmutes)]
1288    pub const fn from_bits(v: u32) -> Self {
1289        // It turns out the safety issues with sNaN were overblown! Hooray!
1290        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1291        unsafe { mem::transmute(v) }
1292    }
1293
1294    /// Returns the memory representation of this floating point number as a byte array in
1295    /// big-endian (network) byte order.
1296    ///
1297    /// See [`from_bits`](Self::from_bits) for some discussion of the
1298    /// portability of this operation (there are almost no issues).
1299    ///
1300    /// # Examples
1301    ///
1302    /// ```
1303    /// let bytes = 12.5f32.to_be_bytes();
1304    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1305    /// ```
1306    #[must_use = "this returns the result of the operation, \
1307                  without modifying the original"]
1308    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1309    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1310    #[inline]
1311    pub const fn to_be_bytes(self) -> [u8; 4] {
1312        self.to_bits().to_be_bytes()
1313    }
1314
1315    /// Returns the memory representation of this floating point number as a byte array in
1316    /// little-endian byte order.
1317    ///
1318    /// See [`from_bits`](Self::from_bits) for some discussion of the
1319    /// portability of this operation (there are almost no issues).
1320    ///
1321    /// # Examples
1322    ///
1323    /// ```
1324    /// let bytes = 12.5f32.to_le_bytes();
1325    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1326    /// ```
1327    #[must_use = "this returns the result of the operation, \
1328                  without modifying the original"]
1329    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1330    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1331    #[inline]
1332    pub const fn to_le_bytes(self) -> [u8; 4] {
1333        self.to_bits().to_le_bytes()
1334    }
1335
1336    /// Returns the memory representation of this floating point number as a byte array in
1337    /// native byte order.
1338    ///
1339    /// As the target platform's native endianness is used, portable code
1340    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1341    ///
1342    /// [`to_be_bytes`]: f32::to_be_bytes
1343    /// [`to_le_bytes`]: f32::to_le_bytes
1344    ///
1345    /// See [`from_bits`](Self::from_bits) for some discussion of the
1346    /// portability of this operation (there are almost no issues).
1347    ///
1348    /// # Examples
1349    ///
1350    /// ```
1351    /// let bytes = 12.5f32.to_ne_bytes();
1352    /// assert_eq!(
1353    ///     bytes,
1354    ///     if cfg!(target_endian = "big") {
1355    ///         [0x41, 0x48, 0x00, 0x00]
1356    ///     } else {
1357    ///         [0x00, 0x00, 0x48, 0x41]
1358    ///     }
1359    /// );
1360    /// ```
1361    #[must_use = "this returns the result of the operation, \
1362                  without modifying the original"]
1363    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1364    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1365    #[inline]
1366    pub const fn to_ne_bytes(self) -> [u8; 4] {
1367        self.to_bits().to_ne_bytes()
1368    }
1369
1370    /// Creates a floating point value from its representation as a byte array in big endian.
1371    ///
1372    /// See [`from_bits`](Self::from_bits) for some discussion of the
1373    /// portability of this operation (there are almost no issues).
1374    ///
1375    /// # Examples
1376    ///
1377    /// ```
1378    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1379    /// assert_eq!(value, 12.5);
1380    /// ```
1381    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1382    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1383    #[must_use]
1384    #[inline]
1385    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1386        Self::from_bits(u32::from_be_bytes(bytes))
1387    }
1388
1389    /// Creates a floating point value from its representation as a byte array in little endian.
1390    ///
1391    /// See [`from_bits`](Self::from_bits) for some discussion of the
1392    /// portability of this operation (there are almost no issues).
1393    ///
1394    /// # Examples
1395    ///
1396    /// ```
1397    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1398    /// assert_eq!(value, 12.5);
1399    /// ```
1400    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1401    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1402    #[must_use]
1403    #[inline]
1404    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1405        Self::from_bits(u32::from_le_bytes(bytes))
1406    }
1407
1408    /// Creates a floating point value from its representation as a byte array in native endian.
1409    ///
1410    /// As the target platform's native endianness is used, portable code
1411    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1412    /// appropriate instead.
1413    ///
1414    /// [`from_be_bytes`]: f32::from_be_bytes
1415    /// [`from_le_bytes`]: f32::from_le_bytes
1416    ///
1417    /// See [`from_bits`](Self::from_bits) for some discussion of the
1418    /// portability of this operation (there are almost no issues).
1419    ///
1420    /// # Examples
1421    ///
1422    /// ```
1423    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1424    ///     [0x41, 0x48, 0x00, 0x00]
1425    /// } else {
1426    ///     [0x00, 0x00, 0x48, 0x41]
1427    /// });
1428    /// assert_eq!(value, 12.5);
1429    /// ```
1430    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1431    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1432    #[must_use]
1433    #[inline]
1434    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1435        Self::from_bits(u32::from_ne_bytes(bytes))
1436    }
1437
1438    /// Returns the ordering between `self` and `other`.
1439    ///
1440    /// Unlike the standard partial comparison between floating point numbers,
1441    /// this comparison always produces an ordering in accordance to
1442    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1443    /// floating point standard. The values are ordered in the following sequence:
1444    ///
1445    /// - negative quiet NaN
1446    /// - negative signaling NaN
1447    /// - negative infinity
1448    /// - negative numbers
1449    /// - negative subnormal numbers
1450    /// - negative zero
1451    /// - positive zero
1452    /// - positive subnormal numbers
1453    /// - positive numbers
1454    /// - positive infinity
1455    /// - positive signaling NaN
1456    /// - positive quiet NaN.
1457    ///
1458    /// The ordering established by this function does not always agree with the
1459    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1460    /// they consider negative and positive zero equal, while `total_cmp`
1461    /// doesn't.
1462    ///
1463    /// The interpretation of the signaling NaN bit follows the definition in
1464    /// the IEEE 754 standard, which may not match the interpretation by some of
1465    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1466    ///
1467    /// # Example
1468    ///
1469    /// ```
1470    /// struct GoodBoy {
1471    ///     name: String,
1472    ///     weight: f32,
1473    /// }
1474    ///
1475    /// let mut bois = vec![
1476    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1477    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1478    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1479    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1480    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1481    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1482    /// ];
1483    ///
1484    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1485    ///
1486    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1487    /// if f32::NAN.is_sign_negative() {
1488    ///     assert!(bois.into_iter().map(|b| b.weight)
1489    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1490    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1491    /// } else {
1492    ///     assert!(bois.into_iter().map(|b| b.weight)
1493    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1494    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1495    /// }
1496    /// ```
1497    #[stable(feature = "total_cmp", since = "1.62.0")]
1498    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1499    #[must_use]
1500    #[inline]
1501    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1502        let mut left = self.to_bits() as i32;
1503        let mut right = other.to_bits() as i32;
1504
1505        // In case of negatives, flip all the bits except the sign
1506        // to achieve a similar layout as two's complement integers
1507        //
1508        // Why does this work? IEEE 754 floats consist of three fields:
1509        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1510        // fields as a whole have the property that their bitwise order is
1511        // equal to the numeric magnitude where the magnitude is defined.
1512        // The magnitude is not normally defined on NaN values, but
1513        // IEEE 754 totalOrder defines the NaN values also to follow the
1514        // bitwise order. This leads to order explained in the doc comment.
1515        // However, the representation of magnitude is the same for negative
1516        // and positive numbers – only the sign bit is different.
1517        // To easily compare the floats as signed integers, we need to
1518        // flip the exponent and mantissa bits in case of negative numbers.
1519        // We effectively convert the numbers to "two's complement" form.
1520        //
1521        // To do the flipping, we construct a mask and XOR against it.
1522        // We branchlessly calculate an "all-ones except for the sign bit"
1523        // mask from negative-signed values: right shifting sign-extends
1524        // the integer, so we "fill" the mask with sign bits, and then
1525        // convert to unsigned to push one more zero bit.
1526        // On positive values, the mask is all zeros, so it's a no-op.
1527        left ^= (((left >> 31) as u32) >> 1) as i32;
1528        right ^= (((right >> 31) as u32) >> 1) as i32;
1529
1530        left.cmp(&right)
1531    }
1532
1533    /// Restrict a value to a certain interval unless it is NaN.
1534    ///
1535    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1536    /// less than `min`. Otherwise this returns `self`.
1537    ///
1538    /// Note that this function returns NaN if the initial value was NaN as
1539    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1540    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1541    ///
1542    /// # Panics
1543    ///
1544    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1545    ///
1546    /// # Examples
1547    ///
1548    /// ```
1549    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1550    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1551    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1552    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1553    ///
1554    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1555    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1556    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1557    /// // This is definitely a negative zero.
1558    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1559    /// ```
1560    #[must_use = "method returns a new number and does not mutate the original value"]
1561    #[stable(feature = "clamp", since = "1.50.0")]
1562    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1563    #[inline]
1564    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1565        const_assert!(
1566            min <= max,
1567            "min > max, or either was NaN",
1568            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1569            min: f32,
1570            max: f32,
1571        );
1572
1573        if self < min {
1574            self = min;
1575        }
1576        if self > max {
1577            self = max;
1578        }
1579        self
1580    }
1581
1582    /// Clamps this number to a symmetric range centered around zero.
1583    ///
1584    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1585    ///
1586    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1587    /// explicit about the intent.
1588    ///
1589    /// # Panics
1590    ///
1591    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1592    ///
1593    /// # Examples
1594    ///
1595    /// ```
1596    /// #![feature(clamp_magnitude)]
1597    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1598    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1599    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1600    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1601    /// ```
1602    #[must_use = "this returns the clamped value and does not modify the original"]
1603    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1604    #[inline]
1605    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1606        assert!(limit >= 0.0, "limit must be non-negative");
1607        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1608        self.clamp(-limit, limit)
1609    }
1610
1611    /// Computes the absolute value of `self`.
1612    ///
1613    /// This function always returns the precise result.
1614    ///
1615    /// # Examples
1616    ///
1617    /// ```
1618    /// let x = 3.5_f32;
1619    /// let y = -3.5_f32;
1620    ///
1621    /// assert_eq!(x.abs(), x);
1622    /// assert_eq!(y.abs(), -y);
1623    ///
1624    /// assert!(f32::NAN.abs().is_nan());
1625    /// ```
1626    #[must_use = "method returns a new number and does not mutate the original value"]
1627    #[stable(feature = "rust1", since = "1.0.0")]
1628    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1629    #[inline]
1630    pub const fn abs(self) -> f32 {
1631        intrinsics::fabs(self)
1632    }
1633
1634    /// Returns a number that represents the sign of `self`.
1635    ///
1636    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1637    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1638    /// - NaN if the number is NaN
1639    ///
1640    /// # Examples
1641    ///
1642    /// ```
1643    /// let f = 3.5_f32;
1644    ///
1645    /// assert_eq!(f.signum(), 1.0);
1646    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1647    ///
1648    /// assert!(f32::NAN.signum().is_nan());
1649    /// ```
1650    #[must_use = "method returns a new number and does not mutate the original value"]
1651    #[stable(feature = "rust1", since = "1.0.0")]
1652    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1653    #[inline]
1654    pub const fn signum(self) -> f32 {
1655        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1656    }
1657
1658    /// Returns a number composed of the magnitude of `self` and the sign of
1659    /// `sign`.
1660    ///
1661    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1662    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1663    /// returned.
1664    ///
1665    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1666    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1667    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1668    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1669    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1670    /// info.
1671    ///
1672    /// # Examples
1673    ///
1674    /// ```
1675    /// let f = 3.5_f32;
1676    ///
1677    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1678    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1679    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1680    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1681    ///
1682    /// assert!(f32::NAN.copysign(1.0).is_nan());
1683    /// ```
1684    #[must_use = "method returns a new number and does not mutate the original value"]
1685    #[inline]
1686    #[stable(feature = "copysign", since = "1.35.0")]
1687    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1688    pub const fn copysign(self, sign: f32) -> f32 {
1689        intrinsics::copysignf32(self, sign)
1690    }
1691
1692    /// Float addition that allows optimizations based on algebraic rules.
1693    ///
1694    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1695    #[must_use = "method returns a new number and does not mutate the original value"]
1696    #[unstable(feature = "float_algebraic", issue = "136469")]
1697    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1698    #[inline]
1699    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1700        intrinsics::fadd_algebraic(self, rhs)
1701    }
1702
1703    /// Float subtraction that allows optimizations based on algebraic rules.
1704    ///
1705    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1706    #[must_use = "method returns a new number and does not mutate the original value"]
1707    #[unstable(feature = "float_algebraic", issue = "136469")]
1708    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1709    #[inline]
1710    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1711        intrinsics::fsub_algebraic(self, rhs)
1712    }
1713
1714    /// Float multiplication that allows optimizations based on algebraic rules.
1715    ///
1716    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1717    #[must_use = "method returns a new number and does not mutate the original value"]
1718    #[unstable(feature = "float_algebraic", issue = "136469")]
1719    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1720    #[inline]
1721    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1722        intrinsics::fmul_algebraic(self, rhs)
1723    }
1724
1725    /// Float division that allows optimizations based on algebraic rules.
1726    ///
1727    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1728    #[must_use = "method returns a new number and does not mutate the original value"]
1729    #[unstable(feature = "float_algebraic", issue = "136469")]
1730    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1731    #[inline]
1732    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1733        intrinsics::fdiv_algebraic(self, rhs)
1734    }
1735
1736    /// Float remainder that allows optimizations based on algebraic rules.
1737    ///
1738    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1739    #[must_use = "method returns a new number and does not mutate the original value"]
1740    #[unstable(feature = "float_algebraic", issue = "136469")]
1741    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1742    #[inline]
1743    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1744        intrinsics::frem_algebraic(self, rhs)
1745    }
1746}
1747
1748/// Experimental implementations of floating point functions in `core`.
1749///
1750/// _The standalone functions in this module are for testing only.
1751/// They will be stabilized as inherent methods._
1752#[unstable(feature = "core_float_math", issue = "137578")]
1753pub mod math {
1754    use crate::intrinsics;
1755    use crate::num::imp::libm;
1756
1757    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1758    ///
1759    /// # Examples
1760    ///
1761    /// ```
1762    /// #![feature(core_float_math)]
1763    ///
1764    /// use core::f32;
1765    ///
1766    /// let f = 3.7_f32;
1767    /// let g = 3.0_f32;
1768    /// let h = -3.7_f32;
1769    ///
1770    /// assert_eq!(f32::math::floor(f), 3.0);
1771    /// assert_eq!(f32::math::floor(g), 3.0);
1772    /// assert_eq!(f32::math::floor(h), -4.0);
1773    /// ```
1774    ///
1775    /// _This standalone function is for testing only.
1776    /// It will be stabilized as an inherent method._
1777    ///
1778    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1779    #[inline]
1780    #[unstable(feature = "core_float_math", issue = "137578")]
1781    #[must_use = "method returns a new number and does not mutate the original value"]
1782    pub const fn floor(x: f32) -> f32 {
1783        intrinsics::floorf32(x)
1784    }
1785
1786    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1787    ///
1788    /// # Examples
1789    ///
1790    /// ```
1791    /// #![feature(core_float_math)]
1792    ///
1793    /// use core::f32;
1794    ///
1795    /// let f = 3.01_f32;
1796    /// let g = 4.0_f32;
1797    ///
1798    /// assert_eq!(f32::math::ceil(f), 4.0);
1799    /// assert_eq!(f32::math::ceil(g), 4.0);
1800    /// ```
1801    ///
1802    /// _This standalone function is for testing only.
1803    /// It will be stabilized as an inherent method._
1804    ///
1805    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1806    #[inline]
1807    #[doc(alias = "ceiling")]
1808    #[must_use = "method returns a new number and does not mutate the original value"]
1809    #[unstable(feature = "core_float_math", issue = "137578")]
1810    pub const fn ceil(x: f32) -> f32 {
1811        intrinsics::ceilf32(x)
1812    }
1813
1814    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1815    ///
1816    /// # Examples
1817    ///
1818    /// ```
1819    /// #![feature(core_float_math)]
1820    ///
1821    /// use core::f32;
1822    ///
1823    /// let f = 3.3_f32;
1824    /// let g = -3.3_f32;
1825    /// let h = -3.7_f32;
1826    /// let i = 3.5_f32;
1827    /// let j = 4.5_f32;
1828    ///
1829    /// assert_eq!(f32::math::round(f), 3.0);
1830    /// assert_eq!(f32::math::round(g), -3.0);
1831    /// assert_eq!(f32::math::round(h), -4.0);
1832    /// assert_eq!(f32::math::round(i), 4.0);
1833    /// assert_eq!(f32::math::round(j), 5.0);
1834    /// ```
1835    ///
1836    /// _This standalone function is for testing only.
1837    /// It will be stabilized as an inherent method._
1838    ///
1839    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1840    #[inline]
1841    #[unstable(feature = "core_float_math", issue = "137578")]
1842    #[must_use = "method returns a new number and does not mutate the original value"]
1843    pub const fn round(x: f32) -> f32 {
1844        intrinsics::roundf32(x)
1845    }
1846
1847    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1848    /// details.
1849    ///
1850    /// # Examples
1851    ///
1852    /// ```
1853    /// #![feature(core_float_math)]
1854    ///
1855    /// use core::f32;
1856    ///
1857    /// let f = 3.3_f32;
1858    /// let g = -3.3_f32;
1859    /// let h = 3.5_f32;
1860    /// let i = 4.5_f32;
1861    ///
1862    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1863    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1864    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1865    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1866    /// ```
1867    ///
1868    /// _This standalone function is for testing only.
1869    /// It will be stabilized as an inherent method._
1870    ///
1871    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1872    #[inline]
1873    #[unstable(feature = "core_float_math", issue = "137578")]
1874    #[must_use = "method returns a new number and does not mutate the original value"]
1875    pub const fn round_ties_even(x: f32) -> f32 {
1876        intrinsics::round_ties_even_f32(x)
1877    }
1878
1879    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1880    ///
1881    /// # Examples
1882    ///
1883    /// ```
1884    /// #![feature(core_float_math)]
1885    ///
1886    /// use core::f32;
1887    ///
1888    /// let f = 3.7_f32;
1889    /// let g = 3.0_f32;
1890    /// let h = -3.7_f32;
1891    ///
1892    /// assert_eq!(f32::math::trunc(f), 3.0);
1893    /// assert_eq!(f32::math::trunc(g), 3.0);
1894    /// assert_eq!(f32::math::trunc(h), -3.0);
1895    /// ```
1896    ///
1897    /// _This standalone function is for testing only.
1898    /// It will be stabilized as an inherent method._
1899    ///
1900    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1901    #[inline]
1902    #[doc(alias = "truncate")]
1903    #[must_use = "method returns a new number and does not mutate the original value"]
1904    #[unstable(feature = "core_float_math", issue = "137578")]
1905    pub const fn trunc(x: f32) -> f32 {
1906        intrinsics::truncf32(x)
1907    }
1908
1909    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1910    ///
1911    /// # Examples
1912    ///
1913    /// ```
1914    /// #![feature(core_float_math)]
1915    ///
1916    /// use core::f32;
1917    ///
1918    /// let x = 3.6_f32;
1919    /// let y = -3.6_f32;
1920    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1921    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1922    ///
1923    /// assert!(abs_difference_x <= f32::EPSILON);
1924    /// assert!(abs_difference_y <= f32::EPSILON);
1925    /// ```
1926    ///
1927    /// _This standalone function is for testing only.
1928    /// It will be stabilized as an inherent method._
1929    ///
1930    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1931    #[inline]
1932    #[unstable(feature = "core_float_math", issue = "137578")]
1933    #[must_use = "method returns a new number and does not mutate the original value"]
1934    pub const fn fract(x: f32) -> f32 {
1935        x - trunc(x)
1936    }
1937
1938    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1939    ///
1940    /// # Examples
1941    ///
1942    /// ```
1943    /// # #![allow(unused_features)]
1944    /// #![feature(core_float_math)]
1945    ///
1946    /// # // FIXME(#140515): mingw has an incorrect fma
1947    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1948    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1949    /// use core::f32;
1950    ///
1951    /// let m = 10.0_f32;
1952    /// let x = 4.0_f32;
1953    /// let b = 60.0_f32;
1954    ///
1955    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1956    /// assert_eq!(m * x + b, 100.0);
1957    ///
1958    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1959    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1960    /// let minus_one = -1.0_f32;
1961    ///
1962    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1963    /// assert_eq!(
1964    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1965    ///     -f32::EPSILON * f32::EPSILON
1966    /// );
1967    /// // Different rounding with the non-fused multiply and add.
1968    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1969    /// # }
1970    /// ```
1971    ///
1972    /// _This standalone function is for testing only.
1973    /// It will be stabilized as an inherent method._
1974    ///
1975    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1976    #[inline]
1977    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1978    #[must_use = "method returns a new number and does not mutate the original value"]
1979    #[unstable(feature = "core_float_math", issue = "137578")]
1980    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1981        intrinsics::fmaf32(x, y, z)
1982    }
1983
1984    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1985    ///
1986    /// # Examples
1987    ///
1988    /// ```
1989    /// #![feature(core_float_math)]
1990    ///
1991    /// use core::f32;
1992    ///
1993    /// let a: f32 = 7.0;
1994    /// let b = 4.0;
1995    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1996    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1997    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1998    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1999    /// ```
2000    ///
2001    /// _This standalone function is for testing only.
2002    /// It will be stabilized as an inherent method._
2003    ///
2004    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
2005    #[inline]
2006    #[unstable(feature = "core_float_math", issue = "137578")]
2007    #[must_use = "method returns a new number and does not mutate the original value"]
2008    pub fn div_euclid(x: f32, rhs: f32) -> f32 {
2009        let q = trunc(x / rhs);
2010        if x % rhs < 0.0 {
2011            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
2012        }
2013        q
2014    }
2015
2016    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
2017    ///
2018    /// # Examples
2019    ///
2020    /// ```
2021    /// #![feature(core_float_math)]
2022    ///
2023    /// use core::f32;
2024    ///
2025    /// let a: f32 = 7.0;
2026    /// let b = 4.0;
2027    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
2028    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
2029    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
2030    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
2031    /// // limitation due to round-off error
2032    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
2033    /// ```
2034    ///
2035    /// _This standalone function is for testing only.
2036    /// It will be stabilized as an inherent method._
2037    ///
2038    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
2039    #[inline]
2040    #[doc(alias = "modulo", alias = "mod")]
2041    #[unstable(feature = "core_float_math", issue = "137578")]
2042    #[must_use = "method returns a new number and does not mutate the original value"]
2043    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
2044        let r = x % rhs;
2045        if r < 0.0 { r + rhs.abs() } else { r }
2046    }
2047
2048    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
2049    ///
2050    /// # Examples
2051    ///
2052    /// ```
2053    /// #![feature(core_float_math)]
2054    ///
2055    /// use core::f32;
2056    ///
2057    /// let x = 2.0_f32;
2058    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
2059    /// assert!(abs_difference <= 1e-5);
2060    ///
2061    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
2062    /// ```
2063    ///
2064    /// _This standalone function is for testing only.
2065    /// It will be stabilized as an inherent method._
2066    ///
2067    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
2068    #[inline]
2069    #[must_use = "method returns a new number and does not mutate the original value"]
2070    #[unstable(feature = "core_float_math", issue = "137578")]
2071    pub fn powi(x: f32, n: i32) -> f32 {
2072        intrinsics::powif32(x, n)
2073    }
2074
2075    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
2076    ///
2077    /// # Examples
2078    ///
2079    /// ```
2080    /// #![feature(core_float_math)]
2081    ///
2082    /// use core::f32;
2083    ///
2084    /// let positive = 4.0_f32;
2085    /// let negative = -4.0_f32;
2086    /// let negative_zero = -0.0_f32;
2087    ///
2088    /// assert_eq!(f32::math::sqrt(positive), 2.0);
2089    /// assert!(f32::math::sqrt(negative).is_nan());
2090    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2091    /// ```
2092    ///
2093    /// _This standalone function is for testing only.
2094    /// It will be stabilized as an inherent method._
2095    ///
2096    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2097    #[inline]
2098    #[doc(alias = "squareRoot")]
2099    #[unstable(feature = "core_float_math", issue = "137578")]
2100    #[must_use = "method returns a new number and does not mutate the original value"]
2101    pub fn sqrt(x: f32) -> f32 {
2102        intrinsics::sqrtf32(x)
2103    }
2104
2105    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2106    ///
2107    /// # Examples
2108    ///
2109    /// ```
2110    /// #![feature(core_float_math)]
2111    ///
2112    /// use core::f32;
2113    ///
2114    /// let x = 3.0f32;
2115    /// let y = -3.0f32;
2116    ///
2117    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2118    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2119    ///
2120    /// assert!(abs_difference_x <= 1e-6);
2121    /// assert!(abs_difference_y <= 1e-6);
2122    /// ```
2123    ///
2124    /// _This standalone function is for testing only.
2125    /// It will be stabilized as an inherent method._
2126    ///
2127    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2128    #[inline]
2129    #[stable(feature = "rust1", since = "1.0.0")]
2130    #[deprecated(
2131        since = "1.10.0",
2132        note = "you probably meant `(self - other).abs()`: \
2133            this operation is `(self - other).max(0.0)` \
2134            except that `abs_sub` also propagates NaNs (also \
2135            known as `fdimf` in C). If you truly need the positive \
2136            difference, consider using that expression or the C function \
2137            `fdimf`, depending on how you wish to handle NaN (please consider \
2138            filing an issue describing your use-case too)."
2139    )]
2140    #[must_use = "method returns a new number and does not mutate the original value"]
2141    pub fn abs_sub(x: f32, other: f32) -> f32 {
2142        libm::fdimf(x, other)
2143    }
2144
2145    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2146    ///
2147    /// # Unspecified precision
2148    ///
2149    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2150    /// can even differ within the same execution from one invocation to the next.
2151    /// This function currently corresponds to the `cbrtf` from libc on Unix
2152    /// and Windows. Note that this might change in the future.
2153    ///
2154    /// # Examples
2155    ///
2156    /// ```
2157    /// #![feature(core_float_math)]
2158    ///
2159    /// use core::f32;
2160    ///
2161    /// let x = 8.0f32;
2162    ///
2163    /// // x^(1/3) - 2 == 0
2164    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2165    ///
2166    /// assert!(abs_difference <= 1e-6);
2167    /// ```
2168    ///
2169    /// _This standalone function is for testing only.
2170    /// It will be stabilized as an inherent method._
2171    ///
2172    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2173    #[inline]
2174    #[must_use = "method returns a new number and does not mutate the original value"]
2175    #[unstable(feature = "core_float_math", issue = "137578")]
2176    pub fn cbrt(x: f32) -> f32 {
2177        libm::cbrtf(x)
2178    }
2179}