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    #[unstable(feature = "more_float_constants", issue = "146939")]
296    pub const PHI: f32 = 1.618033988749894848204586834365638118_f32;
297
298    /// The Euler-Mascheroni constant (γ)
299    #[unstable(feature = "more_float_constants", issue = "146939")]
300    pub const EGAMMA: 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    /// Euler's number (e)
360    #[stable(feature = "rust1", since = "1.0.0")]
361    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
362
363    /// log<sub>2</sub>(e)
364    #[stable(feature = "rust1", since = "1.0.0")]
365    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
366
367    /// log<sub>2</sub>(10)
368    #[stable(feature = "extra_log_consts", since = "1.43.0")]
369    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
370
371    /// log<sub>10</sub>(e)
372    #[stable(feature = "rust1", since = "1.0.0")]
373    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
374
375    /// log<sub>10</sub>(2)
376    #[stable(feature = "extra_log_consts", since = "1.43.0")]
377    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
378
379    /// ln(2)
380    #[stable(feature = "rust1", since = "1.0.0")]
381    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
382
383    /// ln(10)
384    #[stable(feature = "rust1", since = "1.0.0")]
385    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
386}
387
388impl f32 {
389    /// The radix or base of the internal representation of `f32`.
390    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
391    pub const RADIX: u32 = 2;
392
393    /// Number of significant digits in base 2.
394    ///
395    /// Note that the size of the mantissa in the bitwise representation is one
396    /// smaller than this since the leading 1 is not stored explicitly.
397    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
398    pub const MANTISSA_DIGITS: u32 = 24;
399
400    /// Approximate number of significant digits in base 10.
401    ///
402    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
403    /// significant digits can be converted to `f32` and back without loss.
404    ///
405    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
406    ///
407    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
408    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
409    pub const DIGITS: u32 = 6;
410
411    /// [Machine epsilon] value for `f32`.
412    ///
413    /// This is the difference between `1.0` and the next larger representable number.
414    ///
415    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
416    ///
417    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
418    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
419    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
420    #[rustc_diagnostic_item = "f32_epsilon"]
421    pub const EPSILON: f32 = 1.19209290e-07_f32;
422
423    /// Smallest finite `f32` value.
424    ///
425    /// Equal to &minus;[`MAX`].
426    ///
427    /// [`MAX`]: f32::MAX
428    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
429    pub const MIN: f32 = -3.40282347e+38_f32;
430    /// Smallest positive normal `f32` value.
431    ///
432    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
433    ///
434    /// [`MIN_EXP`]: f32::MIN_EXP
435    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
436    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
437    /// Largest finite `f32` value.
438    ///
439    /// Equal to
440    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
441    ///
442    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
443    /// [`MAX_EXP`]: f32::MAX_EXP
444    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
445    pub const MAX: f32 = 3.40282347e+38_f32;
446
447    /// One greater than the minimum possible *normal* power of 2 exponent
448    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
449    ///
450    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
451    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
452    /// In other words, all normal numbers representable by this type are
453    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
454    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
455    pub const MIN_EXP: i32 = -125;
456    /// One greater than the maximum possible power of 2 exponent
457    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
458    ///
459    /// This corresponds to the exact maximum possible power of 2 exponent
460    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
461    /// In other words, all numbers representable by this type are
462    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
463    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
464    pub const MAX_EXP: i32 = 128;
465
466    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
467    ///
468    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
469    ///
470    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
471    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
472    pub const MIN_10_EXP: i32 = -37;
473    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
474    ///
475    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
476    ///
477    /// [`MAX`]: f32::MAX
478    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
479    pub const MAX_10_EXP: i32 = 38;
480
481    /// Not a Number (NaN).
482    ///
483    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
484    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
485    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
486    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
487    /// info.
488    ///
489    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
490    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
491    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
492    /// The concrete bit pattern may change across Rust versions and target platforms.
493    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
494    #[rustc_diagnostic_item = "f32_nan"]
495    #[allow(clippy::eq_op)]
496    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
497    /// Infinity (∞).
498    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
499    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
500    /// Negative infinity (−∞).
501    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
502    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
503
504    /// Sign bit
505    pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
506
507    /// Exponent mask
508    pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
509
510    /// Mantissa mask
511    pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
512
513    /// Minimum representable positive value (min subnormal)
514    const TINY_BITS: u32 = 0x1;
515
516    /// Minimum representable negative value (min negative subnormal)
517    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
518
519    /// Returns `true` if this value is NaN.
520    ///
521    /// ```
522    /// let nan = f32::NAN;
523    /// let f = 7.0_f32;
524    ///
525    /// assert!(nan.is_nan());
526    /// assert!(!f.is_nan());
527    /// ```
528    #[must_use]
529    #[stable(feature = "rust1", since = "1.0.0")]
530    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
531    #[inline]
532    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
533    pub const fn is_nan(self) -> bool {
534        self != self
535    }
536
537    /// Returns `true` if this value is positive infinity or negative infinity, and
538    /// `false` otherwise.
539    ///
540    /// ```
541    /// let f = 7.0f32;
542    /// let inf = f32::INFINITY;
543    /// let neg_inf = f32::NEG_INFINITY;
544    /// let nan = f32::NAN;
545    ///
546    /// assert!(!f.is_infinite());
547    /// assert!(!nan.is_infinite());
548    ///
549    /// assert!(inf.is_infinite());
550    /// assert!(neg_inf.is_infinite());
551    /// ```
552    #[must_use]
553    #[stable(feature = "rust1", since = "1.0.0")]
554    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
555    #[inline]
556    pub const fn is_infinite(self) -> bool {
557        // Getting clever with transmutation can result in incorrect answers on some FPUs
558        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
559        // See https://github.com/rust-lang/rust/issues/72327
560        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
561    }
562
563    /// Returns `true` if this number is neither infinite nor NaN.
564    ///
565    /// ```
566    /// let f = 7.0f32;
567    /// let inf = f32::INFINITY;
568    /// let neg_inf = f32::NEG_INFINITY;
569    /// let nan = f32::NAN;
570    ///
571    /// assert!(f.is_finite());
572    ///
573    /// assert!(!nan.is_finite());
574    /// assert!(!inf.is_finite());
575    /// assert!(!neg_inf.is_finite());
576    /// ```
577    #[must_use]
578    #[stable(feature = "rust1", since = "1.0.0")]
579    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
580    #[inline]
581    pub const fn is_finite(self) -> bool {
582        // There's no need to handle NaN separately: if self is NaN,
583        // the comparison is not true, exactly as desired.
584        self.abs() < Self::INFINITY
585    }
586
587    /// Returns `true` if the number is [subnormal].
588    ///
589    /// ```
590    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
591    /// let max = f32::MAX;
592    /// let lower_than_min = 1.0e-40_f32;
593    /// let zero = 0.0_f32;
594    ///
595    /// assert!(!min.is_subnormal());
596    /// assert!(!max.is_subnormal());
597    ///
598    /// assert!(!zero.is_subnormal());
599    /// assert!(!f32::NAN.is_subnormal());
600    /// assert!(!f32::INFINITY.is_subnormal());
601    /// // Values between `0` and `min` are Subnormal.
602    /// assert!(lower_than_min.is_subnormal());
603    /// ```
604    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
605    #[must_use]
606    #[stable(feature = "is_subnormal", since = "1.53.0")]
607    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
608    #[inline]
609    pub const fn is_subnormal(self) -> bool {
610        matches!(self.classify(), FpCategory::Subnormal)
611    }
612
613    /// Returns `true` if the number is neither zero, infinite,
614    /// [subnormal], or NaN.
615    ///
616    /// ```
617    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
618    /// let max = f32::MAX;
619    /// let lower_than_min = 1.0e-40_f32;
620    /// let zero = 0.0_f32;
621    ///
622    /// assert!(min.is_normal());
623    /// assert!(max.is_normal());
624    ///
625    /// assert!(!zero.is_normal());
626    /// assert!(!f32::NAN.is_normal());
627    /// assert!(!f32::INFINITY.is_normal());
628    /// // Values between `0` and `min` are Subnormal.
629    /// assert!(!lower_than_min.is_normal());
630    /// ```
631    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
632    #[must_use]
633    #[stable(feature = "rust1", since = "1.0.0")]
634    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
635    #[inline]
636    pub const fn is_normal(self) -> bool {
637        matches!(self.classify(), FpCategory::Normal)
638    }
639
640    /// Returns the floating point category of the number. If only one property
641    /// is going to be tested, it is generally faster to use the specific
642    /// predicate instead.
643    ///
644    /// ```
645    /// use std::num::FpCategory;
646    ///
647    /// let num = 12.4_f32;
648    /// let inf = f32::INFINITY;
649    ///
650    /// assert_eq!(num.classify(), FpCategory::Normal);
651    /// assert_eq!(inf.classify(), FpCategory::Infinite);
652    /// ```
653    #[stable(feature = "rust1", since = "1.0.0")]
654    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
655    pub const fn classify(self) -> FpCategory {
656        // We used to have complicated logic here that avoids the simple bit-based tests to work
657        // around buggy codegen for x87 targets (see
658        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
659        // of our tests is able to find any difference between the complicated and the naive
660        // version, so now we are back to the naive version.
661        let b = self.to_bits();
662        match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
663            (0, Self::EXP_MASK) => FpCategory::Infinite,
664            (_, Self::EXP_MASK) => FpCategory::Nan,
665            (0, 0) => FpCategory::Zero,
666            (_, 0) => FpCategory::Subnormal,
667            _ => FpCategory::Normal,
668        }
669    }
670
671    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
672    /// positive sign bit and positive infinity.
673    ///
674    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
675    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
676    /// conserved over arithmetic operations, the result of `is_sign_positive` on
677    /// a NaN might produce an unexpected or non-portable result. See the [specification
678    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
679    /// if you need fully portable behavior (will return `false` for all NaNs).
680    ///
681    /// ```
682    /// let f = 7.0_f32;
683    /// let g = -7.0_f32;
684    ///
685    /// assert!(f.is_sign_positive());
686    /// assert!(!g.is_sign_positive());
687    /// ```
688    #[must_use]
689    #[stable(feature = "rust1", since = "1.0.0")]
690    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
691    #[inline]
692    pub const fn is_sign_positive(self) -> bool {
693        !self.is_sign_negative()
694    }
695
696    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
697    /// negative sign bit and negative infinity.
698    ///
699    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
700    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
701    /// conserved over arithmetic operations, the result of `is_sign_negative` on
702    /// a NaN might produce an unexpected or non-portable result. See the [specification
703    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
704    /// if you need fully portable behavior (will return `false` for all NaNs).
705    ///
706    /// ```
707    /// let f = 7.0f32;
708    /// let g = -7.0f32;
709    ///
710    /// assert!(!f.is_sign_negative());
711    /// assert!(g.is_sign_negative());
712    /// ```
713    #[must_use]
714    #[stable(feature = "rust1", since = "1.0.0")]
715    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
716    #[inline]
717    pub const fn is_sign_negative(self) -> bool {
718        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
719        // applies to zeros and NaNs as well.
720        self.to_bits() & 0x8000_0000 != 0
721    }
722
723    /// Returns the least number greater than `self`.
724    ///
725    /// Let `TINY` be the smallest representable positive `f32`. Then,
726    ///  - if `self.is_nan()`, this returns `self`;
727    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
728    ///  - if `self` is `-TINY`, this returns -0.0;
729    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
730    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
731    ///  - otherwise the unique least value greater than `self` is returned.
732    ///
733    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
734    /// is finite `x == x.next_up().next_down()` also holds.
735    ///
736    /// ```rust
737    /// // f32::EPSILON is the difference between 1.0 and the next number up.
738    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
739    /// // But not for most numbers.
740    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
741    /// assert_eq!(16777216f32.next_up(), 16777218.0);
742    /// ```
743    ///
744    /// This operation corresponds to IEEE-754 `nextUp`.
745    ///
746    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
747    /// [`INFINITY`]: Self::INFINITY
748    /// [`MIN`]: Self::MIN
749    /// [`MAX`]: Self::MAX
750    #[inline]
751    #[doc(alias = "nextUp")]
752    #[stable(feature = "float_next_up_down", since = "1.86.0")]
753    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
754    pub const fn next_up(self) -> Self {
755        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
756        // denormals to zero. This is in general unsound and unsupported, but here
757        // we do our best to still produce the correct result on such targets.
758        let bits = self.to_bits();
759        if self.is_nan() || bits == Self::INFINITY.to_bits() {
760            return self;
761        }
762
763        let abs = bits & !Self::SIGN_MASK;
764        let next_bits = if abs == 0 {
765            Self::TINY_BITS
766        } else if bits == abs {
767            bits + 1
768        } else {
769            bits - 1
770        };
771        Self::from_bits(next_bits)
772    }
773
774    /// Returns the greatest number less than `self`.
775    ///
776    /// Let `TINY` be the smallest representable positive `f32`. Then,
777    ///  - if `self.is_nan()`, this returns `self`;
778    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
779    ///  - if `self` is `TINY`, this returns 0.0;
780    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
781    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
782    ///  - otherwise the unique greatest value less than `self` is returned.
783    ///
784    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
785    /// is finite `x == x.next_down().next_up()` also holds.
786    ///
787    /// ```rust
788    /// let x = 1.0f32;
789    /// // Clamp value into range [0, 1).
790    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
791    /// assert!(clamped < 1.0);
792    /// assert_eq!(clamped.next_up(), 1.0);
793    /// ```
794    ///
795    /// This operation corresponds to IEEE-754 `nextDown`.
796    ///
797    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
798    /// [`INFINITY`]: Self::INFINITY
799    /// [`MIN`]: Self::MIN
800    /// [`MAX`]: Self::MAX
801    #[inline]
802    #[doc(alias = "nextDown")]
803    #[stable(feature = "float_next_up_down", since = "1.86.0")]
804    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
805    pub const fn next_down(self) -> Self {
806        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
807        // denormals to zero. This is in general unsound and unsupported, but here
808        // we do our best to still produce the correct result on such targets.
809        let bits = self.to_bits();
810        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
811            return self;
812        }
813
814        let abs = bits & !Self::SIGN_MASK;
815        let next_bits = if abs == 0 {
816            Self::NEG_TINY_BITS
817        } else if bits == abs {
818            bits - 1
819        } else {
820            bits + 1
821        };
822        Self::from_bits(next_bits)
823    }
824
825    /// Takes the reciprocal (inverse) of a number, `1/x`.
826    ///
827    /// ```
828    /// let x = 2.0_f32;
829    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
830    ///
831    /// assert!(abs_difference <= f32::EPSILON);
832    /// ```
833    #[must_use = "this returns the result of the operation, without modifying the original"]
834    #[stable(feature = "rust1", since = "1.0.0")]
835    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
836    #[inline]
837    pub const fn recip(self) -> f32 {
838        1.0 / self
839    }
840
841    /// Converts radians to degrees.
842    ///
843    /// # Unspecified precision
844    ///
845    /// The precision of this function is non-deterministic. This means it varies by platform,
846    /// Rust version, and can even differ within the same execution from one invocation to the next.
847    ///
848    /// # Examples
849    ///
850    /// ```
851    /// let angle = std::f32::consts::PI;
852    ///
853    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
854    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
855    /// assert!(abs_difference <= f32::EPSILON);
856    /// ```
857    #[must_use = "this returns the result of the operation, \
858                  without modifying the original"]
859    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
860    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
861    #[inline]
862    pub const fn to_degrees(self) -> f32 {
863        // Use a literal to avoid double rounding, consts::PI is already rounded,
864        // and dividing would round again.
865        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
866        self * PIS_IN_180
867    }
868
869    /// Converts degrees to radians.
870    ///
871    /// # Unspecified precision
872    ///
873    /// The precision of this function is non-deterministic. This means it varies by platform,
874    /// Rust version, and can even differ within the same execution from one invocation to the next.
875    ///
876    /// # Examples
877    ///
878    /// ```
879    /// let angle = 180.0f32;
880    ///
881    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
882    ///
883    /// assert!(abs_difference <= f32::EPSILON);
884    /// ```
885    #[must_use = "this returns the result of the operation, \
886                  without modifying the original"]
887    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
888    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
889    #[inline]
890    pub const fn to_radians(self) -> f32 {
891        // The division here is correctly rounded with respect to the true value of π/180.
892        // Although π is irrational and already rounded, the double rounding happens
893        // to produce correct result for f32.
894        const RADS_PER_DEG: f32 = consts::PI / 180.0;
895        self * RADS_PER_DEG
896    }
897
898    /// Returns the maximum of the two numbers, ignoring NaN.
899    ///
900    /// If exactly one of the arguments is NaN, then the other argument is returned. If both
901    /// arguments are NaN, the return value is NaN, with the bit pattern picked using the usual
902    /// [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs compare equal (such
903    /// as for the case of `+0.0` and `-0.0`), either input may be returned non-deterministically.
904    ///
905    /// This follows the IEEE 754-2008 semantics for `maxNum`, except for handling of signaling NaNs;
906    /// this function handles all NaNs the same way and avoids `maxNum`'s problems with associativity.
907    /// This also matches the behavior of libm’s `fmax`.
908    ///
909    /// ```
910    /// let x = 1.0f32;
911    /// let y = 2.0f32;
912    ///
913    /// assert_eq!(x.max(y), y);
914    /// assert_eq!(x.max(f32::NAN), x);
915    /// ```
916    #[must_use = "this returns the result of the comparison, without modifying either input"]
917    #[stable(feature = "rust1", since = "1.0.0")]
918    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
919    #[inline]
920    pub const fn max(self, other: f32) -> f32 {
921        intrinsics::maxnumf32(self, other)
922    }
923
924    /// Returns the minimum of the two numbers, ignoring NaN.
925    ///
926    /// If exactly one of the arguments is NaN, then the other argument is returned. If both
927    /// arguments are NaN, the return value is NaN, with the bit pattern picked using the usual
928    /// [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs compare equal (such
929    /// as for the case of `+0.0` and `-0.0`), either input may be returned non-deterministically.
930    ///
931    /// This follows the IEEE 754-2008 semantics for `minNum`, except for handling of signaling NaNs;
932    /// this function handles all NaNs the same way and avoids `minNum`'s problems with associativity.
933    /// This also matches the behavior of libm’s `fmin`.
934    ///
935    /// ```
936    /// let x = 1.0f32;
937    /// let y = 2.0f32;
938    ///
939    /// assert_eq!(x.min(y), x);
940    /// assert_eq!(x.min(f32::NAN), x);
941    /// ```
942    #[must_use = "this returns the result of the comparison, without modifying either input"]
943    #[stable(feature = "rust1", since = "1.0.0")]
944    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
945    #[inline]
946    pub const fn min(self, other: f32) -> f32 {
947        intrinsics::minnumf32(self, other)
948    }
949
950    /// Returns the maximum of the two numbers, propagating NaN.
951    ///
952    /// This returns NaN when *either* argument is NaN, as opposed to
953    /// [`f32::max`] which only returns NaN when *both* arguments are NaN.
954    ///
955    /// ```
956    /// #![feature(float_minimum_maximum)]
957    /// let x = 1.0f32;
958    /// let y = 2.0f32;
959    ///
960    /// assert_eq!(x.maximum(y), y);
961    /// assert!(x.maximum(f32::NAN).is_nan());
962    /// ```
963    ///
964    /// If one of the arguments is NaN, then NaN is returned. Otherwise this returns the greater
965    /// of the two numbers. For this operation, -0.0 is considered to be less than +0.0.
966    /// Note that this follows the IEEE 754-2019 semantics for `maximum`.
967    ///
968    /// Also note that "propagation" of NaNs here doesn't necessarily mean that the bitpattern of a NaN
969    /// operand is conserved; see the [specification of NaN bit patterns](f32#nan-bit-patterns) for more info.
970    #[must_use = "this returns the result of the comparison, without modifying either input"]
971    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
972    #[inline]
973    pub const fn maximum(self, other: f32) -> f32 {
974        intrinsics::maximumf32(self, other)
975    }
976
977    /// Returns the minimum of the two numbers, propagating NaN.
978    ///
979    /// This returns NaN when *either* argument is NaN, as opposed to
980    /// [`f32::min`] which only returns NaN when *both* arguments are NaN.
981    ///
982    /// ```
983    /// #![feature(float_minimum_maximum)]
984    /// let x = 1.0f32;
985    /// let y = 2.0f32;
986    ///
987    /// assert_eq!(x.minimum(y), x);
988    /// assert!(x.minimum(f32::NAN).is_nan());
989    /// ```
990    ///
991    /// If one of the arguments is NaN, then NaN is returned. Otherwise this returns the lesser
992    /// of the two numbers. For this operation, -0.0 is considered to be less than +0.0.
993    /// Note that this follows the IEEE 754-2019 semantics for `minimum`.
994    ///
995    /// Also note that "propagation" of NaNs here doesn't necessarily mean that the bitpattern of a NaN
996    /// operand is conserved; see the [specification of NaN bit patterns](f32#nan-bit-patterns) for more info.
997    #[must_use = "this returns the result of the comparison, without modifying either input"]
998    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
999    #[inline]
1000    pub const fn minimum(self, other: f32) -> f32 {
1001        intrinsics::minimumf32(self, other)
1002    }
1003
1004    /// Calculates the midpoint (average) between `self` and `rhs`.
1005    ///
1006    /// This returns NaN when *either* argument is NaN or if a combination of
1007    /// +inf and -inf is provided as arguments.
1008    ///
1009    /// # Examples
1010    ///
1011    /// ```
1012    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1013    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1014    /// ```
1015    #[inline]
1016    #[doc(alias = "average")]
1017    #[stable(feature = "num_midpoint", since = "1.85.0")]
1018    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1019    pub const fn midpoint(self, other: f32) -> f32 {
1020        cfg_select! {
1021            // Allow faster implementation that have known good 64-bit float
1022            // implementations. Falling back to the branchy code on targets that don't
1023            // have 64-bit hardware floats or buggy implementations.
1024            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1025            any(
1026                target_arch = "x86_64",
1027                target_arch = "aarch64",
1028                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1029                all(target_arch = "loongarch64", target_feature = "d"),
1030                all(target_arch = "arm", target_feature = "vfp2"),
1031                target_arch = "wasm32",
1032                target_arch = "wasm64",
1033            ) => {
1034                ((self as f64 + other as f64) / 2.0) as f32
1035            }
1036            _ => {
1037                const HI: f32 = f32::MAX / 2.;
1038
1039                let (a, b) = (self, other);
1040                let abs_a = a.abs();
1041                let abs_b = b.abs();
1042
1043                if abs_a <= HI && abs_b <= HI {
1044                    // Overflow is impossible
1045                    (a + b) / 2.
1046                } else {
1047                    (a / 2.) + (b / 2.)
1048                }
1049            }
1050        }
1051    }
1052
1053    /// Rounds toward zero and converts to any primitive integer type,
1054    /// assuming that the value is finite and fits in that type.
1055    ///
1056    /// ```
1057    /// let value = 4.6_f32;
1058    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1059    /// assert_eq!(rounded, 4);
1060    ///
1061    /// let value = -128.9_f32;
1062    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1063    /// assert_eq!(rounded, i8::MIN);
1064    /// ```
1065    ///
1066    /// # Safety
1067    ///
1068    /// The value must:
1069    ///
1070    /// * Not be `NaN`
1071    /// * Not be infinite
1072    /// * Be representable in the return type `Int`, after truncating off its fractional part
1073    #[must_use = "this returns the result of the operation, \
1074                  without modifying the original"]
1075    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1076    #[inline]
1077    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1078    where
1079        Self: FloatToInt<Int>,
1080    {
1081        // SAFETY: the caller must uphold the safety contract for
1082        // `FloatToInt::to_int_unchecked`.
1083        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1084    }
1085
1086    /// Raw transmutation to `u32`.
1087    ///
1088    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1089    ///
1090    /// See [`from_bits`](Self::from_bits) for some discussion of the
1091    /// portability of this operation (there are almost no issues).
1092    ///
1093    /// Note that this function is distinct from `as` casting, which attempts to
1094    /// preserve the *numeric* value, and not the bitwise value.
1095    ///
1096    /// # Examples
1097    ///
1098    /// ```
1099    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1100    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1101    ///
1102    /// ```
1103    #[must_use = "this returns the result of the operation, \
1104                  without modifying the original"]
1105    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1106    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1107    #[inline]
1108    #[allow(unnecessary_transmutes)]
1109    pub const fn to_bits(self) -> u32 {
1110        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1111        unsafe { mem::transmute(self) }
1112    }
1113
1114    /// Raw transmutation from `u32`.
1115    ///
1116    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1117    /// It turns out this is incredibly portable, for two reasons:
1118    ///
1119    /// * Floats and Ints have the same endianness on all supported platforms.
1120    /// * IEEE 754 very precisely specifies the bit layout of floats.
1121    ///
1122    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1123    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1124    /// (notably x86 and ARM) picked the interpretation that was ultimately
1125    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1126    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1127    ///
1128    /// Rather than trying to preserve signaling-ness cross-platform, this
1129    /// implementation favors preserving the exact bits. This means that
1130    /// any payloads encoded in NaNs will be preserved even if the result of
1131    /// this method is sent over the network from an x86 machine to a MIPS one.
1132    ///
1133    /// If the results of this method are only manipulated by the same
1134    /// architecture that produced them, then there is no portability concern.
1135    ///
1136    /// If the input isn't NaN, then there is no portability concern.
1137    ///
1138    /// If you don't care about signalingness (very likely), then there is no
1139    /// portability concern.
1140    ///
1141    /// Note that this function is distinct from `as` casting, which attempts to
1142    /// preserve the *numeric* value, and not the bitwise value.
1143    ///
1144    /// # Examples
1145    ///
1146    /// ```
1147    /// let v = f32::from_bits(0x41480000);
1148    /// assert_eq!(v, 12.5);
1149    /// ```
1150    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1151    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1152    #[must_use]
1153    #[inline]
1154    #[allow(unnecessary_transmutes)]
1155    pub const fn from_bits(v: u32) -> Self {
1156        // It turns out the safety issues with sNaN were overblown! Hooray!
1157        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1158        unsafe { mem::transmute(v) }
1159    }
1160
1161    /// Returns the memory representation of this floating point number as a byte array in
1162    /// big-endian (network) byte order.
1163    ///
1164    /// See [`from_bits`](Self::from_bits) for some discussion of the
1165    /// portability of this operation (there are almost no issues).
1166    ///
1167    /// # Examples
1168    ///
1169    /// ```
1170    /// let bytes = 12.5f32.to_be_bytes();
1171    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1172    /// ```
1173    #[must_use = "this returns the result of the operation, \
1174                  without modifying the original"]
1175    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1176    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1177    #[inline]
1178    pub const fn to_be_bytes(self) -> [u8; 4] {
1179        self.to_bits().to_be_bytes()
1180    }
1181
1182    /// Returns the memory representation of this floating point number as a byte array in
1183    /// little-endian byte order.
1184    ///
1185    /// See [`from_bits`](Self::from_bits) for some discussion of the
1186    /// portability of this operation (there are almost no issues).
1187    ///
1188    /// # Examples
1189    ///
1190    /// ```
1191    /// let bytes = 12.5f32.to_le_bytes();
1192    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1193    /// ```
1194    #[must_use = "this returns the result of the operation, \
1195                  without modifying the original"]
1196    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1197    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1198    #[inline]
1199    pub const fn to_le_bytes(self) -> [u8; 4] {
1200        self.to_bits().to_le_bytes()
1201    }
1202
1203    /// Returns the memory representation of this floating point number as a byte array in
1204    /// native byte order.
1205    ///
1206    /// As the target platform's native endianness is used, portable code
1207    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1208    ///
1209    /// [`to_be_bytes`]: f32::to_be_bytes
1210    /// [`to_le_bytes`]: f32::to_le_bytes
1211    ///
1212    /// See [`from_bits`](Self::from_bits) for some discussion of the
1213    /// portability of this operation (there are almost no issues).
1214    ///
1215    /// # Examples
1216    ///
1217    /// ```
1218    /// let bytes = 12.5f32.to_ne_bytes();
1219    /// assert_eq!(
1220    ///     bytes,
1221    ///     if cfg!(target_endian = "big") {
1222    ///         [0x41, 0x48, 0x00, 0x00]
1223    ///     } else {
1224    ///         [0x00, 0x00, 0x48, 0x41]
1225    ///     }
1226    /// );
1227    /// ```
1228    #[must_use = "this returns the result of the operation, \
1229                  without modifying the original"]
1230    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1231    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1232    #[inline]
1233    pub const fn to_ne_bytes(self) -> [u8; 4] {
1234        self.to_bits().to_ne_bytes()
1235    }
1236
1237    /// Creates a floating point value from its representation as a byte array in big endian.
1238    ///
1239    /// See [`from_bits`](Self::from_bits) for some discussion of the
1240    /// portability of this operation (there are almost no issues).
1241    ///
1242    /// # Examples
1243    ///
1244    /// ```
1245    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1246    /// assert_eq!(value, 12.5);
1247    /// ```
1248    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1249    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1250    #[must_use]
1251    #[inline]
1252    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1253        Self::from_bits(u32::from_be_bytes(bytes))
1254    }
1255
1256    /// Creates a floating point value from its representation as a byte array in little endian.
1257    ///
1258    /// See [`from_bits`](Self::from_bits) for some discussion of the
1259    /// portability of this operation (there are almost no issues).
1260    ///
1261    /// # Examples
1262    ///
1263    /// ```
1264    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1265    /// assert_eq!(value, 12.5);
1266    /// ```
1267    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1268    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1269    #[must_use]
1270    #[inline]
1271    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1272        Self::from_bits(u32::from_le_bytes(bytes))
1273    }
1274
1275    /// Creates a floating point value from its representation as a byte array in native endian.
1276    ///
1277    /// As the target platform's native endianness is used, portable code
1278    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1279    /// appropriate instead.
1280    ///
1281    /// [`from_be_bytes`]: f32::from_be_bytes
1282    /// [`from_le_bytes`]: f32::from_le_bytes
1283    ///
1284    /// See [`from_bits`](Self::from_bits) for some discussion of the
1285    /// portability of this operation (there are almost no issues).
1286    ///
1287    /// # Examples
1288    ///
1289    /// ```
1290    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1291    ///     [0x41, 0x48, 0x00, 0x00]
1292    /// } else {
1293    ///     [0x00, 0x00, 0x48, 0x41]
1294    /// });
1295    /// assert_eq!(value, 12.5);
1296    /// ```
1297    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1298    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1299    #[must_use]
1300    #[inline]
1301    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1302        Self::from_bits(u32::from_ne_bytes(bytes))
1303    }
1304
1305    /// Returns the ordering between `self` and `other`.
1306    ///
1307    /// Unlike the standard partial comparison between floating point numbers,
1308    /// this comparison always produces an ordering in accordance to
1309    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1310    /// floating point standard. The values are ordered in the following sequence:
1311    ///
1312    /// - negative quiet NaN
1313    /// - negative signaling NaN
1314    /// - negative infinity
1315    /// - negative numbers
1316    /// - negative subnormal numbers
1317    /// - negative zero
1318    /// - positive zero
1319    /// - positive subnormal numbers
1320    /// - positive numbers
1321    /// - positive infinity
1322    /// - positive signaling NaN
1323    /// - positive quiet NaN.
1324    ///
1325    /// The ordering established by this function does not always agree with the
1326    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1327    /// they consider negative and positive zero equal, while `total_cmp`
1328    /// doesn't.
1329    ///
1330    /// The interpretation of the signaling NaN bit follows the definition in
1331    /// the IEEE 754 standard, which may not match the interpretation by some of
1332    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1333    ///
1334    /// # Example
1335    ///
1336    /// ```
1337    /// struct GoodBoy {
1338    ///     name: String,
1339    ///     weight: f32,
1340    /// }
1341    ///
1342    /// let mut bois = vec![
1343    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1344    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1345    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1346    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1347    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1348    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1349    /// ];
1350    ///
1351    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1352    ///
1353    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1354    /// if f32::NAN.is_sign_negative() {
1355    ///     assert!(bois.into_iter().map(|b| b.weight)
1356    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1357    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1358    /// } else {
1359    ///     assert!(bois.into_iter().map(|b| b.weight)
1360    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1361    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1362    /// }
1363    /// ```
1364    #[stable(feature = "total_cmp", since = "1.62.0")]
1365    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1366    #[must_use]
1367    #[inline]
1368    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1369        let mut left = self.to_bits() as i32;
1370        let mut right = other.to_bits() as i32;
1371
1372        // In case of negatives, flip all the bits except the sign
1373        // to achieve a similar layout as two's complement integers
1374        //
1375        // Why does this work? IEEE 754 floats consist of three fields:
1376        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1377        // fields as a whole have the property that their bitwise order is
1378        // equal to the numeric magnitude where the magnitude is defined.
1379        // The magnitude is not normally defined on NaN values, but
1380        // IEEE 754 totalOrder defines the NaN values also to follow the
1381        // bitwise order. This leads to order explained in the doc comment.
1382        // However, the representation of magnitude is the same for negative
1383        // and positive numbers – only the sign bit is different.
1384        // To easily compare the floats as signed integers, we need to
1385        // flip the exponent and mantissa bits in case of negative numbers.
1386        // We effectively convert the numbers to "two's complement" form.
1387        //
1388        // To do the flipping, we construct a mask and XOR against it.
1389        // We branchlessly calculate an "all-ones except for the sign bit"
1390        // mask from negative-signed values: right shifting sign-extends
1391        // the integer, so we "fill" the mask with sign bits, and then
1392        // convert to unsigned to push one more zero bit.
1393        // On positive values, the mask is all zeros, so it's a no-op.
1394        left ^= (((left >> 31) as u32) >> 1) as i32;
1395        right ^= (((right >> 31) as u32) >> 1) as i32;
1396
1397        left.cmp(&right)
1398    }
1399
1400    /// Restrict a value to a certain interval unless it is NaN.
1401    ///
1402    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1403    /// less than `min`. Otherwise this returns `self`.
1404    ///
1405    /// Note that this function returns NaN if the initial value was NaN as
1406    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1407    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1408    ///
1409    /// # Panics
1410    ///
1411    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1412    ///
1413    /// # Examples
1414    ///
1415    /// ```
1416    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1417    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1418    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1419    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1420    ///
1421    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1422    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1423    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1424    /// // This is definitely a negative zero.
1425    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1426    /// ```
1427    #[must_use = "method returns a new number and does not mutate the original value"]
1428    #[stable(feature = "clamp", since = "1.50.0")]
1429    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1430    #[inline]
1431    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1432        const_assert!(
1433            min <= max,
1434            "min > max, or either was NaN",
1435            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1436            min: f32,
1437            max: f32,
1438        );
1439
1440        if self < min {
1441            self = min;
1442        }
1443        if self > max {
1444            self = max;
1445        }
1446        self
1447    }
1448
1449    /// Clamps this number to a symmetric range centered around zero.
1450    ///
1451    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1452    ///
1453    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1454    /// explicit about the intent.
1455    ///
1456    /// # Panics
1457    ///
1458    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1459    ///
1460    /// # Examples
1461    ///
1462    /// ```
1463    /// #![feature(clamp_magnitude)]
1464    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1465    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1466    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1467    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1468    /// ```
1469    #[must_use = "this returns the clamped value and does not modify the original"]
1470    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1471    #[inline]
1472    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1473        assert!(limit >= 0.0, "limit must be non-negative");
1474        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1475        self.clamp(-limit, limit)
1476    }
1477
1478    /// Computes the absolute value of `self`.
1479    ///
1480    /// This function always returns the precise result.
1481    ///
1482    /// # Examples
1483    ///
1484    /// ```
1485    /// let x = 3.5_f32;
1486    /// let y = -3.5_f32;
1487    ///
1488    /// assert_eq!(x.abs(), x);
1489    /// assert_eq!(y.abs(), -y);
1490    ///
1491    /// assert!(f32::NAN.abs().is_nan());
1492    /// ```
1493    #[must_use = "method returns a new number and does not mutate the original value"]
1494    #[stable(feature = "rust1", since = "1.0.0")]
1495    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1496    #[inline]
1497    pub const fn abs(self) -> f32 {
1498        intrinsics::fabsf32(self)
1499    }
1500
1501    /// Returns a number that represents the sign of `self`.
1502    ///
1503    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1504    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1505    /// - NaN if the number is NaN
1506    ///
1507    /// # Examples
1508    ///
1509    /// ```
1510    /// let f = 3.5_f32;
1511    ///
1512    /// assert_eq!(f.signum(), 1.0);
1513    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1514    ///
1515    /// assert!(f32::NAN.signum().is_nan());
1516    /// ```
1517    #[must_use = "method returns a new number and does not mutate the original value"]
1518    #[stable(feature = "rust1", since = "1.0.0")]
1519    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1520    #[inline]
1521    pub const fn signum(self) -> f32 {
1522        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1523    }
1524
1525    /// Returns a number composed of the magnitude of `self` and the sign of
1526    /// `sign`.
1527    ///
1528    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1529    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1530    /// returned.
1531    ///
1532    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1533    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1534    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1535    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1536    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1537    /// info.
1538    ///
1539    /// # Examples
1540    ///
1541    /// ```
1542    /// let f = 3.5_f32;
1543    ///
1544    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1545    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1546    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1547    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1548    ///
1549    /// assert!(f32::NAN.copysign(1.0).is_nan());
1550    /// ```
1551    #[must_use = "method returns a new number and does not mutate the original value"]
1552    #[inline]
1553    #[stable(feature = "copysign", since = "1.35.0")]
1554    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1555    pub const fn copysign(self, sign: f32) -> f32 {
1556        intrinsics::copysignf32(self, sign)
1557    }
1558
1559    /// Float addition that allows optimizations based on algebraic rules.
1560    ///
1561    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1562    #[must_use = "method returns a new number and does not mutate the original value"]
1563    #[unstable(feature = "float_algebraic", issue = "136469")]
1564    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1565    #[inline]
1566    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1567        intrinsics::fadd_algebraic(self, rhs)
1568    }
1569
1570    /// Float subtraction that allows optimizations based on algebraic rules.
1571    ///
1572    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1573    #[must_use = "method returns a new number and does not mutate the original value"]
1574    #[unstable(feature = "float_algebraic", issue = "136469")]
1575    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1576    #[inline]
1577    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1578        intrinsics::fsub_algebraic(self, rhs)
1579    }
1580
1581    /// Float multiplication that allows optimizations based on algebraic rules.
1582    ///
1583    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1584    #[must_use = "method returns a new number and does not mutate the original value"]
1585    #[unstable(feature = "float_algebraic", issue = "136469")]
1586    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1587    #[inline]
1588    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1589        intrinsics::fmul_algebraic(self, rhs)
1590    }
1591
1592    /// Float division that allows optimizations based on algebraic rules.
1593    ///
1594    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1595    #[must_use = "method returns a new number and does not mutate the original value"]
1596    #[unstable(feature = "float_algebraic", issue = "136469")]
1597    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1598    #[inline]
1599    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1600        intrinsics::fdiv_algebraic(self, rhs)
1601    }
1602
1603    /// Float remainder that allows optimizations based on algebraic rules.
1604    ///
1605    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1606    #[must_use = "method returns a new number and does not mutate the original value"]
1607    #[unstable(feature = "float_algebraic", issue = "136469")]
1608    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1609    #[inline]
1610    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1611        intrinsics::frem_algebraic(self, rhs)
1612    }
1613}
1614
1615/// Experimental implementations of floating point functions in `core`.
1616///
1617/// _The standalone functions in this module are for testing only.
1618/// They will be stabilized as inherent methods._
1619#[unstable(feature = "core_float_math", issue = "137578")]
1620pub mod math {
1621    use crate::intrinsics;
1622    use crate::num::libm;
1623
1624    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1625    ///
1626    /// # Examples
1627    ///
1628    /// ```
1629    /// #![feature(core_float_math)]
1630    ///
1631    /// use core::f32;
1632    ///
1633    /// let f = 3.7_f32;
1634    /// let g = 3.0_f32;
1635    /// let h = -3.7_f32;
1636    ///
1637    /// assert_eq!(f32::math::floor(f), 3.0);
1638    /// assert_eq!(f32::math::floor(g), 3.0);
1639    /// assert_eq!(f32::math::floor(h), -4.0);
1640    /// ```
1641    ///
1642    /// _This standalone function is for testing only.
1643    /// It will be stabilized as an inherent method._
1644    ///
1645    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1646    #[inline]
1647    #[unstable(feature = "core_float_math", issue = "137578")]
1648    #[must_use = "method returns a new number and does not mutate the original value"]
1649    pub const fn floor(x: f32) -> f32 {
1650        intrinsics::floorf32(x)
1651    }
1652
1653    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1654    ///
1655    /// # Examples
1656    ///
1657    /// ```
1658    /// #![feature(core_float_math)]
1659    ///
1660    /// use core::f32;
1661    ///
1662    /// let f = 3.01_f32;
1663    /// let g = 4.0_f32;
1664    ///
1665    /// assert_eq!(f32::math::ceil(f), 4.0);
1666    /// assert_eq!(f32::math::ceil(g), 4.0);
1667    /// ```
1668    ///
1669    /// _This standalone function is for testing only.
1670    /// It will be stabilized as an inherent method._
1671    ///
1672    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1673    #[inline]
1674    #[doc(alias = "ceiling")]
1675    #[must_use = "method returns a new number and does not mutate the original value"]
1676    #[unstable(feature = "core_float_math", issue = "137578")]
1677    pub const fn ceil(x: f32) -> f32 {
1678        intrinsics::ceilf32(x)
1679    }
1680
1681    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1682    ///
1683    /// # Examples
1684    ///
1685    /// ```
1686    /// #![feature(core_float_math)]
1687    ///
1688    /// use core::f32;
1689    ///
1690    /// let f = 3.3_f32;
1691    /// let g = -3.3_f32;
1692    /// let h = -3.7_f32;
1693    /// let i = 3.5_f32;
1694    /// let j = 4.5_f32;
1695    ///
1696    /// assert_eq!(f32::math::round(f), 3.0);
1697    /// assert_eq!(f32::math::round(g), -3.0);
1698    /// assert_eq!(f32::math::round(h), -4.0);
1699    /// assert_eq!(f32::math::round(i), 4.0);
1700    /// assert_eq!(f32::math::round(j), 5.0);
1701    /// ```
1702    ///
1703    /// _This standalone function is for testing only.
1704    /// It will be stabilized as an inherent method._
1705    ///
1706    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1707    #[inline]
1708    #[unstable(feature = "core_float_math", issue = "137578")]
1709    #[must_use = "method returns a new number and does not mutate the original value"]
1710    pub const fn round(x: f32) -> f32 {
1711        intrinsics::roundf32(x)
1712    }
1713
1714    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1715    /// details.
1716    ///
1717    /// # Examples
1718    ///
1719    /// ```
1720    /// #![feature(core_float_math)]
1721    ///
1722    /// use core::f32;
1723    ///
1724    /// let f = 3.3_f32;
1725    /// let g = -3.3_f32;
1726    /// let h = 3.5_f32;
1727    /// let i = 4.5_f32;
1728    ///
1729    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1730    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1731    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1732    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1733    /// ```
1734    ///
1735    /// _This standalone function is for testing only.
1736    /// It will be stabilized as an inherent method._
1737    ///
1738    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1739    #[inline]
1740    #[unstable(feature = "core_float_math", issue = "137578")]
1741    #[must_use = "method returns a new number and does not mutate the original value"]
1742    pub const fn round_ties_even(x: f32) -> f32 {
1743        intrinsics::round_ties_even_f32(x)
1744    }
1745
1746    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1747    ///
1748    /// # Examples
1749    ///
1750    /// ```
1751    /// #![feature(core_float_math)]
1752    ///
1753    /// use core::f32;
1754    ///
1755    /// let f = 3.7_f32;
1756    /// let g = 3.0_f32;
1757    /// let h = -3.7_f32;
1758    ///
1759    /// assert_eq!(f32::math::trunc(f), 3.0);
1760    /// assert_eq!(f32::math::trunc(g), 3.0);
1761    /// assert_eq!(f32::math::trunc(h), -3.0);
1762    /// ```
1763    ///
1764    /// _This standalone function is for testing only.
1765    /// It will be stabilized as an inherent method._
1766    ///
1767    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1768    #[inline]
1769    #[doc(alias = "truncate")]
1770    #[must_use = "method returns a new number and does not mutate the original value"]
1771    #[unstable(feature = "core_float_math", issue = "137578")]
1772    pub const fn trunc(x: f32) -> f32 {
1773        intrinsics::truncf32(x)
1774    }
1775
1776    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1777    ///
1778    /// # Examples
1779    ///
1780    /// ```
1781    /// #![feature(core_float_math)]
1782    ///
1783    /// use core::f32;
1784    ///
1785    /// let x = 3.6_f32;
1786    /// let y = -3.6_f32;
1787    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1788    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1789    ///
1790    /// assert!(abs_difference_x <= f32::EPSILON);
1791    /// assert!(abs_difference_y <= f32::EPSILON);
1792    /// ```
1793    ///
1794    /// _This standalone function is for testing only.
1795    /// It will be stabilized as an inherent method._
1796    ///
1797    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1798    #[inline]
1799    #[unstable(feature = "core_float_math", issue = "137578")]
1800    #[must_use = "method returns a new number and does not mutate the original value"]
1801    pub const fn fract(x: f32) -> f32 {
1802        x - trunc(x)
1803    }
1804
1805    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1806    ///
1807    /// # Examples
1808    ///
1809    /// ```
1810    /// #![feature(core_float_math)]
1811    ///
1812    /// # // FIXME(#140515): mingw has an incorrect fma
1813    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1814    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1815    /// use core::f32;
1816    ///
1817    /// let m = 10.0_f32;
1818    /// let x = 4.0_f32;
1819    /// let b = 60.0_f32;
1820    ///
1821    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1822    /// assert_eq!(m * x + b, 100.0);
1823    ///
1824    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1825    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1826    /// let minus_one = -1.0_f32;
1827    ///
1828    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1829    /// assert_eq!(
1830    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1831    ///     -f32::EPSILON * f32::EPSILON
1832    /// );
1833    /// // Different rounding with the non-fused multiply and add.
1834    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1835    /// # }
1836    /// ```
1837    ///
1838    /// _This standalone function is for testing only.
1839    /// It will be stabilized as an inherent method._
1840    ///
1841    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1842    #[inline]
1843    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1844    #[must_use = "method returns a new number and does not mutate the original value"]
1845    #[unstable(feature = "core_float_math", issue = "137578")]
1846    #[rustc_const_unstable(feature = "const_mul_add", issue = "146724")]
1847    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1848        intrinsics::fmaf32(x, y, z)
1849    }
1850
1851    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1852    ///
1853    /// # Examples
1854    ///
1855    /// ```
1856    /// #![feature(core_float_math)]
1857    ///
1858    /// use core::f32;
1859    ///
1860    /// let a: f32 = 7.0;
1861    /// let b = 4.0;
1862    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1863    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1864    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1865    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1866    /// ```
1867    ///
1868    /// _This standalone function is for testing only.
1869    /// It will be stabilized as an inherent method._
1870    ///
1871    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
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 fn div_euclid(x: f32, rhs: f32) -> f32 {
1876        let q = trunc(x / rhs);
1877        if x % rhs < 0.0 {
1878            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
1879        }
1880        q
1881    }
1882
1883    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
1884    ///
1885    /// # Examples
1886    ///
1887    /// ```
1888    /// #![feature(core_float_math)]
1889    ///
1890    /// use core::f32;
1891    ///
1892    /// let a: f32 = 7.0;
1893    /// let b = 4.0;
1894    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
1895    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
1896    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
1897    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
1898    /// // limitation due to round-off error
1899    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
1900    /// ```
1901    ///
1902    /// _This standalone function is for testing only.
1903    /// It will be stabilized as an inherent method._
1904    ///
1905    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
1906    #[inline]
1907    #[doc(alias = "modulo", alias = "mod")]
1908    #[unstable(feature = "core_float_math", issue = "137578")]
1909    #[must_use = "method returns a new number and does not mutate the original value"]
1910    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
1911        let r = x % rhs;
1912        if r < 0.0 { r + rhs.abs() } else { r }
1913    }
1914
1915    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
1916    ///
1917    /// # Examples
1918    ///
1919    /// ```
1920    /// #![feature(core_float_math)]
1921    ///
1922    /// use core::f32;
1923    ///
1924    /// let x = 2.0_f32;
1925    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
1926    /// assert!(abs_difference <= 1e-5);
1927    ///
1928    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
1929    /// ```
1930    ///
1931    /// _This standalone function is for testing only.
1932    /// It will be stabilized as an inherent method._
1933    ///
1934    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
1935    #[inline]
1936    #[must_use = "method returns a new number and does not mutate the original value"]
1937    #[unstable(feature = "core_float_math", issue = "137578")]
1938    pub fn powi(x: f32, n: i32) -> f32 {
1939        intrinsics::powif32(x, n)
1940    }
1941
1942    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
1943    ///
1944    /// # Examples
1945    ///
1946    /// ```
1947    /// #![feature(core_float_math)]
1948    ///
1949    /// use core::f32;
1950    ///
1951    /// let positive = 4.0_f32;
1952    /// let negative = -4.0_f32;
1953    /// let negative_zero = -0.0_f32;
1954    ///
1955    /// assert_eq!(f32::math::sqrt(positive), 2.0);
1956    /// assert!(f32::math::sqrt(negative).is_nan());
1957    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
1958    /// ```
1959    ///
1960    /// _This standalone function is for testing only.
1961    /// It will be stabilized as an inherent method._
1962    ///
1963    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
1964    #[inline]
1965    #[doc(alias = "squareRoot")]
1966    #[unstable(feature = "core_float_math", issue = "137578")]
1967    #[must_use = "method returns a new number and does not mutate the original value"]
1968    pub fn sqrt(x: f32) -> f32 {
1969        intrinsics::sqrtf32(x)
1970    }
1971
1972    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
1973    ///
1974    /// # Examples
1975    ///
1976    /// ```
1977    /// #![feature(core_float_math)]
1978    ///
1979    /// use core::f32;
1980    ///
1981    /// let x = 3.0f32;
1982    /// let y = -3.0f32;
1983    ///
1984    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
1985    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
1986    ///
1987    /// assert!(abs_difference_x <= 1e-6);
1988    /// assert!(abs_difference_y <= 1e-6);
1989    /// ```
1990    ///
1991    /// _This standalone function is for testing only.
1992    /// It will be stabilized as an inherent method._
1993    ///
1994    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
1995    #[inline]
1996    #[stable(feature = "rust1", since = "1.0.0")]
1997    #[deprecated(
1998        since = "1.10.0",
1999        note = "you probably meant `(self - other).abs()`: \
2000            this operation is `(self - other).max(0.0)` \
2001            except that `abs_sub` also propagates NaNs (also \
2002            known as `fdimf` in C). If you truly need the positive \
2003            difference, consider using that expression or the C function \
2004            `fdimf`, depending on how you wish to handle NaN (please consider \
2005            filing an issue describing your use-case too)."
2006    )]
2007    #[must_use = "method returns a new number and does not mutate the original value"]
2008    pub fn abs_sub(x: f32, other: f32) -> f32 {
2009        libm::fdimf(x, other)
2010    }
2011
2012    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2013    ///
2014    /// # Unspecified precision
2015    ///
2016    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2017    /// can even differ within the same execution from one invocation to the next.
2018    /// This function currently corresponds to the `cbrtf` from libc on Unix
2019    /// and Windows. Note that this might change in the future.
2020    ///
2021    /// # Examples
2022    ///
2023    /// ```
2024    /// #![feature(core_float_math)]
2025    ///
2026    /// use core::f32;
2027    ///
2028    /// let x = 8.0f32;
2029    ///
2030    /// // x^(1/3) - 2 == 0
2031    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2032    ///
2033    /// assert!(abs_difference <= 1e-6);
2034    /// ```
2035    ///
2036    /// _This standalone function is for testing only.
2037    /// It will be stabilized as an inherent method._
2038    ///
2039    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2040    #[inline]
2041    #[must_use = "method returns a new number and does not mutate the original value"]
2042    #[unstable(feature = "core_float_math", issue = "137578")]
2043    pub fn cbrt(x: f32) -> f32 {
2044        libm::cbrtf(x)
2045    }
2046}