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::{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")]
280pub mod consts {
281    // FIXME: replace with mathematical constants from cmath.
282
283    /// Archimedes' constant (π)
284    #[stable(feature = "rust1", since = "1.0.0")]
285    pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
286
287    /// The full circle constant (τ)
288    ///
289    /// Equal to 2π.
290    #[stable(feature = "tau_constant", since = "1.47.0")]
291    pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
292
293    /// The golden ratio (φ)
294    #[unstable(feature = "more_float_constants", issue = "103883")]
295    pub const PHI: f32 = 1.618033988749894848204586834365638118_f32;
296
297    /// The Euler-Mascheroni constant (γ)
298    #[unstable(feature = "more_float_constants", issue = "103883")]
299    pub const EGAMMA: f32 = 0.577215664901532860606512090082402431_f32;
300
301    /// π/2
302    #[stable(feature = "rust1", since = "1.0.0")]
303    pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
304
305    /// π/3
306    #[stable(feature = "rust1", since = "1.0.0")]
307    pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
308
309    /// π/4
310    #[stable(feature = "rust1", since = "1.0.0")]
311    pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
312
313    /// π/6
314    #[stable(feature = "rust1", since = "1.0.0")]
315    pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
316
317    /// π/8
318    #[stable(feature = "rust1", since = "1.0.0")]
319    pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
320
321    /// 1/π
322    #[stable(feature = "rust1", since = "1.0.0")]
323    pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
324
325    /// 1/sqrt(π)
326    #[unstable(feature = "more_float_constants", issue = "103883")]
327    pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
328
329    /// 1/sqrt(2π)
330    #[doc(alias = "FRAC_1_SQRT_TAU")]
331    #[unstable(feature = "more_float_constants", issue = "103883")]
332    pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
333
334    /// 2/π
335    #[stable(feature = "rust1", since = "1.0.0")]
336    pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
337
338    /// 2/sqrt(π)
339    #[stable(feature = "rust1", since = "1.0.0")]
340    pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
341
342    /// sqrt(2)
343    #[stable(feature = "rust1", since = "1.0.0")]
344    pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
345
346    /// 1/sqrt(2)
347    #[stable(feature = "rust1", since = "1.0.0")]
348    pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
349
350    /// sqrt(3)
351    #[unstable(feature = "more_float_constants", issue = "103883")]
352    pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
353
354    /// 1/sqrt(3)
355    #[unstable(feature = "more_float_constants", issue = "103883")]
356    pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
357
358    /// Euler's number (e)
359    #[stable(feature = "rust1", since = "1.0.0")]
360    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
361
362    /// log<sub>2</sub>(e)
363    #[stable(feature = "rust1", since = "1.0.0")]
364    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
365
366    /// log<sub>2</sub>(10)
367    #[stable(feature = "extra_log_consts", since = "1.43.0")]
368    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
369
370    /// log<sub>10</sub>(e)
371    #[stable(feature = "rust1", since = "1.0.0")]
372    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
373
374    /// log<sub>10</sub>(2)
375    #[stable(feature = "extra_log_consts", since = "1.43.0")]
376    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
377
378    /// ln(2)
379    #[stable(feature = "rust1", since = "1.0.0")]
380    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
381
382    /// ln(10)
383    #[stable(feature = "rust1", since = "1.0.0")]
384    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
385}
386
387impl f32 {
388    /// The radix or base of the internal representation of `f32`.
389    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
390    pub const RADIX: u32 = 2;
391
392    /// Number of significant digits in base 2.
393    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
394    pub const MANTISSA_DIGITS: u32 = 24;
395
396    /// Approximate number of significant digits in base 10.
397    ///
398    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
399    /// significant digits can be converted to `f32` and back without loss.
400    ///
401    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
402    ///
403    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
404    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
405    pub const DIGITS: u32 = 6;
406
407    /// [Machine epsilon] value for `f32`.
408    ///
409    /// This is the difference between `1.0` and the next larger representable number.
410    ///
411    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
412    ///
413    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
414    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
415    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
416    #[rustc_diagnostic_item = "f32_epsilon"]
417    pub const EPSILON: f32 = 1.19209290e-07_f32;
418
419    /// Smallest finite `f32` value.
420    ///
421    /// Equal to &minus;[`MAX`].
422    ///
423    /// [`MAX`]: f32::MAX
424    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
425    pub const MIN: f32 = -3.40282347e+38_f32;
426    /// Smallest positive normal `f32` value.
427    ///
428    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
429    ///
430    /// [`MIN_EXP`]: f32::MIN_EXP
431    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
432    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
433    /// Largest finite `f32` value.
434    ///
435    /// Equal to
436    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
437    ///
438    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
439    /// [`MAX_EXP`]: f32::MAX_EXP
440    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
441    pub const MAX: f32 = 3.40282347e+38_f32;
442
443    /// One greater than the minimum possible normal power of 2 exponent.
444    ///
445    /// If <i>x</i>&nbsp;=&nbsp;`MIN_EXP`, then normal numbers
446    /// ≥&nbsp;0.5&nbsp;×&nbsp;2<sup><i>x</i></sup>.
447    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
448    pub const MIN_EXP: i32 = -125;
449    /// Maximum possible power of 2 exponent.
450    ///
451    /// If <i>x</i>&nbsp;=&nbsp;`MAX_EXP`, then normal numbers
452    /// &lt;&nbsp;1&nbsp;×&nbsp;2<sup><i>x</i></sup>.
453    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
454    pub const MAX_EXP: i32 = 128;
455
456    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
457    ///
458    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
459    ///
460    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
461    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
462    pub const MIN_10_EXP: i32 = -37;
463    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
464    ///
465    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
466    ///
467    /// [`MAX`]: f32::MAX
468    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
469    pub const MAX_10_EXP: i32 = 38;
470
471    /// Not a Number (NaN).
472    ///
473    /// Note that IEEE 754 doesn't define just a single NaN value;
474    /// a plethora of bit patterns are considered to be NaN.
475    /// Furthermore, the standard makes a difference
476    /// between a "signaling" and a "quiet" NaN,
477    /// and allows inspecting its "payload" (the unspecified bits in the bit pattern).
478    /// This constant isn't guaranteed to equal to any specific NaN bitpattern,
479    /// and the stability of its representation over Rust versions
480    /// and target platforms isn't guaranteed.
481    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
482    #[rustc_diagnostic_item = "f32_nan"]
483    #[allow(clippy::eq_op)]
484    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
485    /// Infinity (∞).
486    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
487    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
488    /// Negative infinity (−∞).
489    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
490    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
491
492    /// Sign bit
493    pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
494
495    /// Exponent mask
496    pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
497
498    /// Mantissa mask
499    pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
500
501    /// Minimum representable positive value (min subnormal)
502    const TINY_BITS: u32 = 0x1;
503
504    /// Minimum representable negative value (min negative subnormal)
505    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
506
507    /// Returns `true` if this value is NaN.
508    ///
509    /// ```
510    /// let nan = f32::NAN;
511    /// let f = 7.0_f32;
512    ///
513    /// assert!(nan.is_nan());
514    /// assert!(!f.is_nan());
515    /// ```
516    #[must_use]
517    #[stable(feature = "rust1", since = "1.0.0")]
518    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
519    #[inline]
520    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
521    pub const fn is_nan(self) -> bool {
522        self != self
523    }
524
525    /// Returns `true` if this value is positive infinity or negative infinity, and
526    /// `false` otherwise.
527    ///
528    /// ```
529    /// let f = 7.0f32;
530    /// let inf = f32::INFINITY;
531    /// let neg_inf = f32::NEG_INFINITY;
532    /// let nan = f32::NAN;
533    ///
534    /// assert!(!f.is_infinite());
535    /// assert!(!nan.is_infinite());
536    ///
537    /// assert!(inf.is_infinite());
538    /// assert!(neg_inf.is_infinite());
539    /// ```
540    #[must_use]
541    #[stable(feature = "rust1", since = "1.0.0")]
542    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
543    #[inline]
544    pub const fn is_infinite(self) -> bool {
545        // Getting clever with transmutation can result in incorrect answers on some FPUs
546        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
547        // See https://github.com/rust-lang/rust/issues/72327
548        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
549    }
550
551    /// Returns `true` if this number is neither infinite nor NaN.
552    ///
553    /// ```
554    /// let f = 7.0f32;
555    /// let inf = f32::INFINITY;
556    /// let neg_inf = f32::NEG_INFINITY;
557    /// let nan = f32::NAN;
558    ///
559    /// assert!(f.is_finite());
560    ///
561    /// assert!(!nan.is_finite());
562    /// assert!(!inf.is_finite());
563    /// assert!(!neg_inf.is_finite());
564    /// ```
565    #[must_use]
566    #[stable(feature = "rust1", since = "1.0.0")]
567    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
568    #[inline]
569    pub const fn is_finite(self) -> bool {
570        // There's no need to handle NaN separately: if self is NaN,
571        // the comparison is not true, exactly as desired.
572        self.abs() < Self::INFINITY
573    }
574
575    /// Returns `true` if the number is [subnormal].
576    ///
577    /// ```
578    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
579    /// let max = f32::MAX;
580    /// let lower_than_min = 1.0e-40_f32;
581    /// let zero = 0.0_f32;
582    ///
583    /// assert!(!min.is_subnormal());
584    /// assert!(!max.is_subnormal());
585    ///
586    /// assert!(!zero.is_subnormal());
587    /// assert!(!f32::NAN.is_subnormal());
588    /// assert!(!f32::INFINITY.is_subnormal());
589    /// // Values between `0` and `min` are Subnormal.
590    /// assert!(lower_than_min.is_subnormal());
591    /// ```
592    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
593    #[must_use]
594    #[stable(feature = "is_subnormal", since = "1.53.0")]
595    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
596    #[inline]
597    pub const fn is_subnormal(self) -> bool {
598        matches!(self.classify(), FpCategory::Subnormal)
599    }
600
601    /// Returns `true` if the number is neither zero, infinite,
602    /// [subnormal], or NaN.
603    ///
604    /// ```
605    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
606    /// let max = f32::MAX;
607    /// let lower_than_min = 1.0e-40_f32;
608    /// let zero = 0.0_f32;
609    ///
610    /// assert!(min.is_normal());
611    /// assert!(max.is_normal());
612    ///
613    /// assert!(!zero.is_normal());
614    /// assert!(!f32::NAN.is_normal());
615    /// assert!(!f32::INFINITY.is_normal());
616    /// // Values between `0` and `min` are Subnormal.
617    /// assert!(!lower_than_min.is_normal());
618    /// ```
619    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
620    #[must_use]
621    #[stable(feature = "rust1", since = "1.0.0")]
622    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
623    #[inline]
624    pub const fn is_normal(self) -> bool {
625        matches!(self.classify(), FpCategory::Normal)
626    }
627
628    /// Returns the floating point category of the number. If only one property
629    /// is going to be tested, it is generally faster to use the specific
630    /// predicate instead.
631    ///
632    /// ```
633    /// use std::num::FpCategory;
634    ///
635    /// let num = 12.4_f32;
636    /// let inf = f32::INFINITY;
637    ///
638    /// assert_eq!(num.classify(), FpCategory::Normal);
639    /// assert_eq!(inf.classify(), FpCategory::Infinite);
640    /// ```
641    #[stable(feature = "rust1", since = "1.0.0")]
642    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
643    pub const fn classify(self) -> FpCategory {
644        // We used to have complicated logic here that avoids the simple bit-based tests to work
645        // around buggy codegen for x87 targets (see
646        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
647        // of our tests is able to find any difference between the complicated and the naive
648        // version, so now we are back to the naive version.
649        let b = self.to_bits();
650        match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
651            (0, Self::EXP_MASK) => FpCategory::Infinite,
652            (_, Self::EXP_MASK) => FpCategory::Nan,
653            (0, 0) => FpCategory::Zero,
654            (_, 0) => FpCategory::Subnormal,
655            _ => FpCategory::Normal,
656        }
657    }
658
659    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
660    /// positive sign bit and positive infinity.
661    ///
662    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
663    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
664    /// conserved over arithmetic operations, the result of `is_sign_positive` on
665    /// a NaN might produce an unexpected or non-portable result. See the [specification
666    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
667    /// if you need fully portable behavior (will return `false` for all NaNs).
668    ///
669    /// ```
670    /// let f = 7.0_f32;
671    /// let g = -7.0_f32;
672    ///
673    /// assert!(f.is_sign_positive());
674    /// assert!(!g.is_sign_positive());
675    /// ```
676    #[must_use]
677    #[stable(feature = "rust1", since = "1.0.0")]
678    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
679    #[inline]
680    pub const fn is_sign_positive(self) -> bool {
681        !self.is_sign_negative()
682    }
683
684    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
685    /// negative sign bit and negative infinity.
686    ///
687    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
688    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
689    /// conserved over arithmetic operations, the result of `is_sign_negative` on
690    /// a NaN might produce an unexpected or non-portable result. See the [specification
691    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
692    /// if you need fully portable behavior (will return `false` for all NaNs).
693    ///
694    /// ```
695    /// let f = 7.0f32;
696    /// let g = -7.0f32;
697    ///
698    /// assert!(!f.is_sign_negative());
699    /// assert!(g.is_sign_negative());
700    /// ```
701    #[must_use]
702    #[stable(feature = "rust1", since = "1.0.0")]
703    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
704    #[inline]
705    pub const fn is_sign_negative(self) -> bool {
706        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
707        // applies to zeros and NaNs as well.
708        // SAFETY: This is just transmuting to get the sign bit, it's fine.
709        unsafe { mem::transmute::<f32, u32>(self) & 0x8000_0000 != 0 }
710    }
711
712    /// Returns the least number greater than `self`.
713    ///
714    /// Let `TINY` be the smallest representable positive `f32`. Then,
715    ///  - if `self.is_nan()`, this returns `self`;
716    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
717    ///  - if `self` is `-TINY`, this returns -0.0;
718    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
719    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
720    ///  - otherwise the unique least value greater than `self` is returned.
721    ///
722    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
723    /// is finite `x == x.next_up().next_down()` also holds.
724    ///
725    /// ```rust
726    /// // f32::EPSILON is the difference between 1.0 and the next number up.
727    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
728    /// // But not for most numbers.
729    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
730    /// assert_eq!(16777216f32.next_up(), 16777218.0);
731    /// ```
732    ///
733    /// This operation corresponds to IEEE-754 `nextUp`.
734    ///
735    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
736    /// [`INFINITY`]: Self::INFINITY
737    /// [`MIN`]: Self::MIN
738    /// [`MAX`]: Self::MAX
739    #[inline]
740    #[doc(alias = "nextUp")]
741    #[stable(feature = "float_next_up_down", since = "1.86.0")]
742    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
743    pub const fn next_up(self) -> Self {
744        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
745        // denormals to zero. This is in general unsound and unsupported, but here
746        // we do our best to still produce the correct result on such targets.
747        let bits = self.to_bits();
748        if self.is_nan() || bits == Self::INFINITY.to_bits() {
749            return self;
750        }
751
752        let abs = bits & !Self::SIGN_MASK;
753        let next_bits = if abs == 0 {
754            Self::TINY_BITS
755        } else if bits == abs {
756            bits + 1
757        } else {
758            bits - 1
759        };
760        Self::from_bits(next_bits)
761    }
762
763    /// Returns the greatest number less than `self`.
764    ///
765    /// Let `TINY` be the smallest representable positive `f32`. Then,
766    ///  - if `self.is_nan()`, this returns `self`;
767    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
768    ///  - if `self` is `TINY`, this returns 0.0;
769    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
770    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
771    ///  - otherwise the unique greatest value less than `self` is returned.
772    ///
773    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
774    /// is finite `x == x.next_down().next_up()` also holds.
775    ///
776    /// ```rust
777    /// let x = 1.0f32;
778    /// // Clamp value into range [0, 1).
779    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
780    /// assert!(clamped < 1.0);
781    /// assert_eq!(clamped.next_up(), 1.0);
782    /// ```
783    ///
784    /// This operation corresponds to IEEE-754 `nextDown`.
785    ///
786    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
787    /// [`INFINITY`]: Self::INFINITY
788    /// [`MIN`]: Self::MIN
789    /// [`MAX`]: Self::MAX
790    #[inline]
791    #[doc(alias = "nextDown")]
792    #[stable(feature = "float_next_up_down", since = "1.86.0")]
793    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
794    pub const fn next_down(self) -> Self {
795        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
796        // denormals to zero. This is in general unsound and unsupported, but here
797        // we do our best to still produce the correct result on such targets.
798        let bits = self.to_bits();
799        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
800            return self;
801        }
802
803        let abs = bits & !Self::SIGN_MASK;
804        let next_bits = if abs == 0 {
805            Self::NEG_TINY_BITS
806        } else if bits == abs {
807            bits - 1
808        } else {
809            bits + 1
810        };
811        Self::from_bits(next_bits)
812    }
813
814    /// Takes the reciprocal (inverse) of a number, `1/x`.
815    ///
816    /// ```
817    /// let x = 2.0_f32;
818    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
819    ///
820    /// assert!(abs_difference <= f32::EPSILON);
821    /// ```
822    #[must_use = "this returns the result of the operation, without modifying the original"]
823    #[stable(feature = "rust1", since = "1.0.0")]
824    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
825    #[inline]
826    pub const fn recip(self) -> f32 {
827        1.0 / self
828    }
829
830    /// Converts radians to degrees.
831    ///
832    /// ```
833    /// let angle = std::f32::consts::PI;
834    ///
835    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
836    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
837    /// assert!(abs_difference <= f32::EPSILON);
838    /// ```
839    #[must_use = "this returns the result of the operation, \
840                  without modifying the original"]
841    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
842    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
843    #[inline]
844    pub const fn to_degrees(self) -> f32 {
845        // Use a constant for better precision.
846        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
847        self * PIS_IN_180
848    }
849
850    /// Converts degrees to radians.
851    ///
852    /// ```
853    /// let angle = 180.0f32;
854    ///
855    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
856    ///
857    /// assert!(abs_difference <= f32::EPSILON);
858    /// ```
859    #[must_use = "this returns the result of the operation, \
860                  without modifying the original"]
861    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
862    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
863    #[inline]
864    pub const fn to_radians(self) -> f32 {
865        const RADS_PER_DEG: f32 = consts::PI / 180.0;
866        self * RADS_PER_DEG
867    }
868
869    /// Returns the maximum of the two numbers, ignoring NaN.
870    ///
871    /// If one of the arguments is NaN, then the other argument is returned.
872    /// This follows the IEEE 754-2008 semantics for maxNum, except for handling of signaling NaNs;
873    /// this function handles all NaNs the same way and avoids maxNum's problems with associativity.
874    /// This also matches the behavior of libm’s fmax. In particular, if the inputs compare equal
875    /// (such as for the case of `+0.0` and `-0.0`), either input may be returned non-deterministically.
876    ///
877    /// ```
878    /// let x = 1.0f32;
879    /// let y = 2.0f32;
880    ///
881    /// assert_eq!(x.max(y), y);
882    /// ```
883    #[must_use = "this returns the result of the comparison, without modifying either input"]
884    #[stable(feature = "rust1", since = "1.0.0")]
885    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
886    #[inline]
887    pub const fn max(self, other: f32) -> f32 {
888        intrinsics::maxnumf32(self, other)
889    }
890
891    /// Returns the minimum of the two numbers, ignoring NaN.
892    ///
893    /// If one of the arguments is NaN, then the other argument is returned.
894    /// This follows the IEEE 754-2008 semantics for minNum, except for handling of signaling NaNs;
895    /// this function handles all NaNs the same way and avoids minNum's problems with associativity.
896    /// This also matches the behavior of libm’s fmin. In particular, if the inputs compare equal
897    /// (such as for the case of `+0.0` and `-0.0`), either input may be returned non-deterministically.
898    ///
899    /// ```
900    /// let x = 1.0f32;
901    /// let y = 2.0f32;
902    ///
903    /// assert_eq!(x.min(y), x);
904    /// ```
905    #[must_use = "this returns the result of the comparison, without modifying either input"]
906    #[stable(feature = "rust1", since = "1.0.0")]
907    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
908    #[inline]
909    pub const fn min(self, other: f32) -> f32 {
910        intrinsics::minnumf32(self, other)
911    }
912
913    /// Returns the maximum of the two numbers, propagating NaN.
914    ///
915    /// This returns NaN when *either* argument is NaN, as opposed to
916    /// [`f32::max`] which only returns NaN when *both* arguments are NaN.
917    ///
918    /// ```
919    /// #![feature(float_minimum_maximum)]
920    /// let x = 1.0f32;
921    /// let y = 2.0f32;
922    ///
923    /// assert_eq!(x.maximum(y), y);
924    /// assert!(x.maximum(f32::NAN).is_nan());
925    /// ```
926    ///
927    /// If one of the arguments is NaN, then NaN is returned. Otherwise this returns the greater
928    /// of the two numbers. For this operation, -0.0 is considered to be less than +0.0.
929    /// Note that this follows the semantics specified in IEEE 754-2019.
930    ///
931    /// Also note that "propagation" of NaNs here doesn't necessarily mean that the bitpattern of a NaN
932    /// operand is conserved; see the [specification of NaN bit patterns](f32#nan-bit-patterns) for more info.
933    #[must_use = "this returns the result of the comparison, without modifying either input"]
934    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
935    #[inline]
936    pub const fn maximum(self, other: f32) -> f32 {
937        if self > other {
938            self
939        } else if other > self {
940            other
941        } else if self == other {
942            if self.is_sign_positive() && other.is_sign_negative() { self } else { other }
943        } else {
944            self + other
945        }
946    }
947
948    /// Returns the minimum of the two numbers, propagating NaN.
949    ///
950    /// This returns NaN when *either* argument is NaN, as opposed to
951    /// [`f32::min`] which only returns NaN when *both* arguments are NaN.
952    ///
953    /// ```
954    /// #![feature(float_minimum_maximum)]
955    /// let x = 1.0f32;
956    /// let y = 2.0f32;
957    ///
958    /// assert_eq!(x.minimum(y), x);
959    /// assert!(x.minimum(f32::NAN).is_nan());
960    /// ```
961    ///
962    /// If one of the arguments is NaN, then NaN is returned. Otherwise this returns the lesser
963    /// of the two numbers. For this operation, -0.0 is considered to be less than +0.0.
964    /// Note that this follows the semantics specified in IEEE 754-2019.
965    ///
966    /// Also note that "propagation" of NaNs here doesn't necessarily mean that the bitpattern of a NaN
967    /// operand is conserved; see the [specification of NaN bit patterns](f32#nan-bit-patterns) for more info.
968    #[must_use = "this returns the result of the comparison, without modifying either input"]
969    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
970    #[inline]
971    pub const fn minimum(self, other: f32) -> f32 {
972        if self < other {
973            self
974        } else if other < self {
975            other
976        } else if self == other {
977            if self.is_sign_negative() && other.is_sign_positive() { self } else { other }
978        } else {
979            // At least one input is NaN. Use `+` to perform NaN propagation and quieting.
980            self + other
981        }
982    }
983
984    /// Calculates the middle point of `self` and `rhs`.
985    ///
986    /// This returns NaN when *either* argument is NaN or if a combination of
987    /// +inf and -inf is provided as arguments.
988    ///
989    /// # Examples
990    ///
991    /// ```
992    /// assert_eq!(1f32.midpoint(4.0), 2.5);
993    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
994    /// ```
995    #[inline]
996    #[stable(feature = "num_midpoint", since = "1.85.0")]
997    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
998    pub const fn midpoint(self, other: f32) -> f32 {
999        cfg_if! {
1000            // Allow faster implementation that have known good 64-bit float
1001            // implementations. Falling back to the branchy code on targets that don't
1002            // have 64-bit hardware floats or buggy implementations.
1003            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1004            if #[cfg(any(
1005                    target_arch = "x86_64",
1006                    target_arch = "aarch64",
1007                    all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1008                    all(target_arch = "arm", target_feature = "vfp2"),
1009                    target_arch = "wasm32",
1010                    target_arch = "wasm64",
1011                ))] {
1012                ((self as f64 + other as f64) / 2.0) as f32
1013            } else {
1014                const LO: f32 = f32::MIN_POSITIVE * 2.;
1015                const HI: f32 = f32::MAX / 2.;
1016
1017                let (a, b) = (self, other);
1018                let abs_a = a.abs();
1019                let abs_b = b.abs();
1020
1021                if abs_a <= HI && abs_b <= HI {
1022                    // Overflow is impossible
1023                    (a + b) / 2.
1024                } else if abs_a < LO {
1025                    // Not safe to halve `a` (would underflow)
1026                    a + (b / 2.)
1027                } else if abs_b < LO {
1028                    // Not safe to halve `b` (would underflow)
1029                    (a / 2.) + b
1030                } else {
1031                    // Safe to halve `a` and `b`
1032                    (a / 2.) + (b / 2.)
1033                }
1034            }
1035        }
1036    }
1037
1038    /// Rounds toward zero and converts to any primitive integer type,
1039    /// assuming that the value is finite and fits in that type.
1040    ///
1041    /// ```
1042    /// let value = 4.6_f32;
1043    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1044    /// assert_eq!(rounded, 4);
1045    ///
1046    /// let value = -128.9_f32;
1047    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1048    /// assert_eq!(rounded, i8::MIN);
1049    /// ```
1050    ///
1051    /// # Safety
1052    ///
1053    /// The value must:
1054    ///
1055    /// * Not be `NaN`
1056    /// * Not be infinite
1057    /// * Be representable in the return type `Int`, after truncating off its fractional part
1058    #[must_use = "this returns the result of the operation, \
1059                  without modifying the original"]
1060    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1061    #[inline]
1062    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1063    where
1064        Self: FloatToInt<Int>,
1065    {
1066        // SAFETY: the caller must uphold the safety contract for
1067        // `FloatToInt::to_int_unchecked`.
1068        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1069    }
1070
1071    /// Raw transmutation to `u32`.
1072    ///
1073    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1074    ///
1075    /// See [`from_bits`](Self::from_bits) for some discussion of the
1076    /// portability of this operation (there are almost no issues).
1077    ///
1078    /// Note that this function is distinct from `as` casting, which attempts to
1079    /// preserve the *numeric* value, and not the bitwise value.
1080    ///
1081    /// # Examples
1082    ///
1083    /// ```
1084    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1085    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1086    ///
1087    /// ```
1088    #[must_use = "this returns the result of the operation, \
1089                  without modifying the original"]
1090    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1091    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1092    #[inline]
1093    pub const fn to_bits(self) -> u32 {
1094        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1095        unsafe { mem::transmute(self) }
1096    }
1097
1098    /// Raw transmutation from `u32`.
1099    ///
1100    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1101    /// It turns out this is incredibly portable, for two reasons:
1102    ///
1103    /// * Floats and Ints have the same endianness on all supported platforms.
1104    /// * IEEE 754 very precisely specifies the bit layout of floats.
1105    ///
1106    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1107    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1108    /// (notably x86 and ARM) picked the interpretation that was ultimately
1109    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1110    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1111    ///
1112    /// Rather than trying to preserve signaling-ness cross-platform, this
1113    /// implementation favors preserving the exact bits. This means that
1114    /// any payloads encoded in NaNs will be preserved even if the result of
1115    /// this method is sent over the network from an x86 machine to a MIPS one.
1116    ///
1117    /// If the results of this method are only manipulated by the same
1118    /// architecture that produced them, then there is no portability concern.
1119    ///
1120    /// If the input isn't NaN, then there is no portability concern.
1121    ///
1122    /// If you don't care about signalingness (very likely), then there is no
1123    /// portability concern.
1124    ///
1125    /// Note that this function is distinct from `as` casting, which attempts to
1126    /// preserve the *numeric* value, and not the bitwise value.
1127    ///
1128    /// # Examples
1129    ///
1130    /// ```
1131    /// let v = f32::from_bits(0x41480000);
1132    /// assert_eq!(v, 12.5);
1133    /// ```
1134    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1135    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1136    #[must_use]
1137    #[inline]
1138    pub const fn from_bits(v: u32) -> Self {
1139        // It turns out the safety issues with sNaN were overblown! Hooray!
1140        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1141        unsafe { mem::transmute(v) }
1142    }
1143
1144    /// Returns the memory representation of this floating point number as a byte array in
1145    /// big-endian (network) byte order.
1146    ///
1147    /// See [`from_bits`](Self::from_bits) for some discussion of the
1148    /// portability of this operation (there are almost no issues).
1149    ///
1150    /// # Examples
1151    ///
1152    /// ```
1153    /// let bytes = 12.5f32.to_be_bytes();
1154    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1155    /// ```
1156    #[must_use = "this returns the result of the operation, \
1157                  without modifying the original"]
1158    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1159    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1160    #[inline]
1161    pub const fn to_be_bytes(self) -> [u8; 4] {
1162        self.to_bits().to_be_bytes()
1163    }
1164
1165    /// Returns the memory representation of this floating point number as a byte array in
1166    /// little-endian byte order.
1167    ///
1168    /// See [`from_bits`](Self::from_bits) for some discussion of the
1169    /// portability of this operation (there are almost no issues).
1170    ///
1171    /// # Examples
1172    ///
1173    /// ```
1174    /// let bytes = 12.5f32.to_le_bytes();
1175    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1176    /// ```
1177    #[must_use = "this returns the result of the operation, \
1178                  without modifying the original"]
1179    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1180    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1181    #[inline]
1182    pub const fn to_le_bytes(self) -> [u8; 4] {
1183        self.to_bits().to_le_bytes()
1184    }
1185
1186    /// Returns the memory representation of this floating point number as a byte array in
1187    /// native byte order.
1188    ///
1189    /// As the target platform's native endianness is used, portable code
1190    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1191    ///
1192    /// [`to_be_bytes`]: f32::to_be_bytes
1193    /// [`to_le_bytes`]: f32::to_le_bytes
1194    ///
1195    /// See [`from_bits`](Self::from_bits) for some discussion of the
1196    /// portability of this operation (there are almost no issues).
1197    ///
1198    /// # Examples
1199    ///
1200    /// ```
1201    /// let bytes = 12.5f32.to_ne_bytes();
1202    /// assert_eq!(
1203    ///     bytes,
1204    ///     if cfg!(target_endian = "big") {
1205    ///         [0x41, 0x48, 0x00, 0x00]
1206    ///     } else {
1207    ///         [0x00, 0x00, 0x48, 0x41]
1208    ///     }
1209    /// );
1210    /// ```
1211    #[must_use = "this returns the result of the operation, \
1212                  without modifying the original"]
1213    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1214    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1215    #[inline]
1216    pub const fn to_ne_bytes(self) -> [u8; 4] {
1217        self.to_bits().to_ne_bytes()
1218    }
1219
1220    /// Creates a floating point value from its representation as a byte array in big endian.
1221    ///
1222    /// See [`from_bits`](Self::from_bits) for some discussion of the
1223    /// portability of this operation (there are almost no issues).
1224    ///
1225    /// # Examples
1226    ///
1227    /// ```
1228    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1229    /// assert_eq!(value, 12.5);
1230    /// ```
1231    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1232    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1233    #[must_use]
1234    #[inline]
1235    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1236        Self::from_bits(u32::from_be_bytes(bytes))
1237    }
1238
1239    /// Creates a floating point value from its representation as a byte array in little endian.
1240    ///
1241    /// See [`from_bits`](Self::from_bits) for some discussion of the
1242    /// portability of this operation (there are almost no issues).
1243    ///
1244    /// # Examples
1245    ///
1246    /// ```
1247    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1248    /// assert_eq!(value, 12.5);
1249    /// ```
1250    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1251    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1252    #[must_use]
1253    #[inline]
1254    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1255        Self::from_bits(u32::from_le_bytes(bytes))
1256    }
1257
1258    /// Creates a floating point value from its representation as a byte array in native endian.
1259    ///
1260    /// As the target platform's native endianness is used, portable code
1261    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1262    /// appropriate instead.
1263    ///
1264    /// [`from_be_bytes`]: f32::from_be_bytes
1265    /// [`from_le_bytes`]: f32::from_le_bytes
1266    ///
1267    /// See [`from_bits`](Self::from_bits) for some discussion of the
1268    /// portability of this operation (there are almost no issues).
1269    ///
1270    /// # Examples
1271    ///
1272    /// ```
1273    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1274    ///     [0x41, 0x48, 0x00, 0x00]
1275    /// } else {
1276    ///     [0x00, 0x00, 0x48, 0x41]
1277    /// });
1278    /// assert_eq!(value, 12.5);
1279    /// ```
1280    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1281    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1282    #[must_use]
1283    #[inline]
1284    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1285        Self::from_bits(u32::from_ne_bytes(bytes))
1286    }
1287
1288    /// Returns the ordering between `self` and `other`.
1289    ///
1290    /// Unlike the standard partial comparison between floating point numbers,
1291    /// this comparison always produces an ordering in accordance to
1292    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1293    /// floating point standard. The values are ordered in the following sequence:
1294    ///
1295    /// - negative quiet NaN
1296    /// - negative signaling NaN
1297    /// - negative infinity
1298    /// - negative numbers
1299    /// - negative subnormal numbers
1300    /// - negative zero
1301    /// - positive zero
1302    /// - positive subnormal numbers
1303    /// - positive numbers
1304    /// - positive infinity
1305    /// - positive signaling NaN
1306    /// - positive quiet NaN.
1307    ///
1308    /// The ordering established by this function does not always agree with the
1309    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1310    /// they consider negative and positive zero equal, while `total_cmp`
1311    /// doesn't.
1312    ///
1313    /// The interpretation of the signaling NaN bit follows the definition in
1314    /// the IEEE 754 standard, which may not match the interpretation by some of
1315    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1316    ///
1317    /// # Example
1318    ///
1319    /// ```
1320    /// struct GoodBoy {
1321    ///     name: String,
1322    ///     weight: f32,
1323    /// }
1324    ///
1325    /// let mut bois = vec![
1326    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1327    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1328    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1329    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1330    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1331    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1332    /// ];
1333    ///
1334    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1335    ///
1336    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1337    /// if f32::NAN.is_sign_negative() {
1338    ///     assert!(bois.into_iter().map(|b| b.weight)
1339    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1340    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1341    /// } else {
1342    ///     assert!(bois.into_iter().map(|b| b.weight)
1343    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1344    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1345    /// }
1346    /// ```
1347    #[stable(feature = "total_cmp", since = "1.62.0")]
1348    #[must_use]
1349    #[inline]
1350    pub fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1351        let mut left = self.to_bits() as i32;
1352        let mut right = other.to_bits() as i32;
1353
1354        // In case of negatives, flip all the bits except the sign
1355        // to achieve a similar layout as two's complement integers
1356        //
1357        // Why does this work? IEEE 754 floats consist of three fields:
1358        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1359        // fields as a whole have the property that their bitwise order is
1360        // equal to the numeric magnitude where the magnitude is defined.
1361        // The magnitude is not normally defined on NaN values, but
1362        // IEEE 754 totalOrder defines the NaN values also to follow the
1363        // bitwise order. This leads to order explained in the doc comment.
1364        // However, the representation of magnitude is the same for negative
1365        // and positive numbers – only the sign bit is different.
1366        // To easily compare the floats as signed integers, we need to
1367        // flip the exponent and mantissa bits in case of negative numbers.
1368        // We effectively convert the numbers to "two's complement" form.
1369        //
1370        // To do the flipping, we construct a mask and XOR against it.
1371        // We branchlessly calculate an "all-ones except for the sign bit"
1372        // mask from negative-signed values: right shifting sign-extends
1373        // the integer, so we "fill" the mask with sign bits, and then
1374        // convert to unsigned to push one more zero bit.
1375        // On positive values, the mask is all zeros, so it's a no-op.
1376        left ^= (((left >> 31) as u32) >> 1) as i32;
1377        right ^= (((right >> 31) as u32) >> 1) as i32;
1378
1379        left.cmp(&right)
1380    }
1381
1382    /// Restrict a value to a certain interval unless it is NaN.
1383    ///
1384    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1385    /// less than `min`. Otherwise this returns `self`.
1386    ///
1387    /// Note that this function returns NaN if the initial value was NaN as
1388    /// well.
1389    ///
1390    /// # Panics
1391    ///
1392    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1393    ///
1394    /// # Examples
1395    ///
1396    /// ```
1397    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1398    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1399    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1400    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1401    /// ```
1402    #[must_use = "method returns a new number and does not mutate the original value"]
1403    #[stable(feature = "clamp", since = "1.50.0")]
1404    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1405    #[inline]
1406    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1407        const_assert!(
1408            min <= max,
1409            "min > max, or either was NaN",
1410            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1411            min: f32,
1412            max: f32,
1413        );
1414
1415        if self < min {
1416            self = min;
1417        }
1418        if self > max {
1419            self = max;
1420        }
1421        self
1422    }
1423
1424    /// Computes the absolute value of `self`.
1425    ///
1426    /// This function always returns the precise result.
1427    ///
1428    /// # Examples
1429    ///
1430    /// ```
1431    /// let x = 3.5_f32;
1432    /// let y = -3.5_f32;
1433    ///
1434    /// assert_eq!(x.abs(), x);
1435    /// assert_eq!(y.abs(), -y);
1436    ///
1437    /// assert!(f32::NAN.abs().is_nan());
1438    /// ```
1439    #[must_use = "method returns a new number and does not mutate the original value"]
1440    #[stable(feature = "rust1", since = "1.0.0")]
1441    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1442    #[inline]
1443    pub const fn abs(self) -> f32 {
1444        // SAFETY: this is actually a safe intrinsic
1445        unsafe { intrinsics::fabsf32(self) }
1446    }
1447
1448    /// Returns a number that represents the sign of `self`.
1449    ///
1450    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1451    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1452    /// - NaN if the number is NaN
1453    ///
1454    /// # Examples
1455    ///
1456    /// ```
1457    /// let f = 3.5_f32;
1458    ///
1459    /// assert_eq!(f.signum(), 1.0);
1460    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1461    ///
1462    /// assert!(f32::NAN.signum().is_nan());
1463    /// ```
1464    #[must_use = "method returns a new number and does not mutate the original value"]
1465    #[stable(feature = "rust1", since = "1.0.0")]
1466    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1467    #[inline]
1468    pub const fn signum(self) -> f32 {
1469        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1470    }
1471
1472    /// Returns a number composed of the magnitude of `self` and the sign of
1473    /// `sign`.
1474    ///
1475    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1476    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1477    /// returned.
1478    ///
1479    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1480    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1481    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1482    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1483    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1484    /// info.
1485    ///
1486    /// # Examples
1487    ///
1488    /// ```
1489    /// let f = 3.5_f32;
1490    ///
1491    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1492    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1493    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1494    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1495    ///
1496    /// assert!(f32::NAN.copysign(1.0).is_nan());
1497    /// ```
1498    #[must_use = "method returns a new number and does not mutate the original value"]
1499    #[inline]
1500    #[stable(feature = "copysign", since = "1.35.0")]
1501    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1502    pub const fn copysign(self, sign: f32) -> f32 {
1503        // SAFETY: this is actually a safe intrinsic
1504        unsafe { intrinsics::copysignf32(self, sign) }
1505    }
1506}