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
14#[cfg(not(feature = "ferrocene_subset"))]
15use crate::convert::FloatToInt;
16#[cfg(not(feature = "ferrocene_subset"))]
17use crate::num::FpCategory;
18#[cfg(not(feature = "ferrocene_subset"))]
19use crate::panic::const_assert;
20#[cfg(not(feature = "ferrocene_subset"))]
21use crate::{cfg_select, intrinsics, mem};
22
23// Ferrocene addition: imports for certified subset
24#[cfg(feature = "ferrocene_subset")]
25#[rustfmt::skip]
26use crate::{intrinsics, mem};
27
28/// The radix or base of the internal representation of `f32`.
29/// Use [`f32::RADIX`] instead.
30///
31/// # Examples
32///
33/// ```rust
34/// // deprecated way
35/// # #[allow(deprecated, deprecated_in_future)]
36/// let r = std::f32::RADIX;
37///
38/// // intended way
39/// let r = f32::RADIX;
40/// ```
41#[stable(feature = "rust1", since = "1.0.0")]
42#[deprecated(since = "TBD", note = "replaced by the `RADIX` associated constant on `f32`")]
43#[rustc_diagnostic_item = "f32_legacy_const_radix"]
44pub const RADIX: u32 = f32::RADIX;
45
46/// Number of significant digits in base 2.
47/// Use [`f32::MANTISSA_DIGITS`] instead.
48///
49/// # Examples
50///
51/// ```rust
52/// // deprecated way
53/// # #[allow(deprecated, deprecated_in_future)]
54/// let d = std::f32::MANTISSA_DIGITS;
55///
56/// // intended way
57/// let d = f32::MANTISSA_DIGITS;
58/// ```
59#[stable(feature = "rust1", since = "1.0.0")]
60#[deprecated(
61 since = "TBD",
62 note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
63)]
64#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
65pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
66
67/// Approximate number of significant digits in base 10.
68/// Use [`f32::DIGITS`] instead.
69///
70/// # Examples
71///
72/// ```rust
73/// // deprecated way
74/// # #[allow(deprecated, deprecated_in_future)]
75/// let d = std::f32::DIGITS;
76///
77/// // intended way
78/// let d = f32::DIGITS;
79/// ```
80#[stable(feature = "rust1", since = "1.0.0")]
81#[deprecated(since = "TBD", note = "replaced by the `DIGITS` associated constant on `f32`")]
82#[rustc_diagnostic_item = "f32_legacy_const_digits"]
83pub const DIGITS: u32 = f32::DIGITS;
84
85/// [Machine epsilon] value for `f32`.
86/// Use [`f32::EPSILON`] instead.
87///
88/// This is the difference between `1.0` and the next larger representable number.
89///
90/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
91///
92/// # Examples
93///
94/// ```rust
95/// // deprecated way
96/// # #[allow(deprecated, deprecated_in_future)]
97/// let e = std::f32::EPSILON;
98///
99/// // intended way
100/// let e = f32::EPSILON;
101/// ```
102#[stable(feature = "rust1", since = "1.0.0")]
103#[deprecated(since = "TBD", note = "replaced by the `EPSILON` associated constant on `f32`")]
104#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
105pub const EPSILON: f32 = f32::EPSILON;
106
107/// Smallest finite `f32` value.
108/// Use [`f32::MIN`] instead.
109///
110/// # Examples
111///
112/// ```rust
113/// // deprecated way
114/// # #[allow(deprecated, deprecated_in_future)]
115/// let min = std::f32::MIN;
116///
117/// // intended way
118/// let min = f32::MIN;
119/// ```
120#[stable(feature = "rust1", since = "1.0.0")]
121#[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on `f32`")]
122#[rustc_diagnostic_item = "f32_legacy_const_min"]
123pub const MIN: f32 = f32::MIN;
124
125/// Smallest positive normal `f32` value.
126/// Use [`f32::MIN_POSITIVE`] instead.
127///
128/// # Examples
129///
130/// ```rust
131/// // deprecated way
132/// # #[allow(deprecated, deprecated_in_future)]
133/// let min = std::f32::MIN_POSITIVE;
134///
135/// // intended way
136/// let min = f32::MIN_POSITIVE;
137/// ```
138#[stable(feature = "rust1", since = "1.0.0")]
139#[deprecated(since = "TBD", note = "replaced by the `MIN_POSITIVE` associated constant on `f32`")]
140#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
141pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
142
143/// Largest finite `f32` value.
144/// Use [`f32::MAX`] instead.
145///
146/// # Examples
147///
148/// ```rust
149/// // deprecated way
150/// # #[allow(deprecated, deprecated_in_future)]
151/// let max = std::f32::MAX;
152///
153/// // intended way
154/// let max = f32::MAX;
155/// ```
156#[stable(feature = "rust1", since = "1.0.0")]
157#[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on `f32`")]
158#[rustc_diagnostic_item = "f32_legacy_const_max"]
159pub const MAX: f32 = f32::MAX;
160
161/// One greater than the minimum possible normal power of 2 exponent.
162/// Use [`f32::MIN_EXP`] instead.
163///
164/// # Examples
165///
166/// ```rust
167/// // deprecated way
168/// # #[allow(deprecated, deprecated_in_future)]
169/// let min = std::f32::MIN_EXP;
170///
171/// // intended way
172/// let min = f32::MIN_EXP;
173/// ```
174#[stable(feature = "rust1", since = "1.0.0")]
175#[deprecated(since = "TBD", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
176#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
177pub const MIN_EXP: i32 = f32::MIN_EXP;
178
179/// Maximum possible power of 2 exponent.
180/// Use [`f32::MAX_EXP`] instead.
181///
182/// # Examples
183///
184/// ```rust
185/// // deprecated way
186/// # #[allow(deprecated, deprecated_in_future)]
187/// let max = std::f32::MAX_EXP;
188///
189/// // intended way
190/// let max = f32::MAX_EXP;
191/// ```
192#[stable(feature = "rust1", since = "1.0.0")]
193#[deprecated(since = "TBD", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
194#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
195pub const MAX_EXP: i32 = f32::MAX_EXP;
196
197/// Minimum possible normal power of 10 exponent.
198/// Use [`f32::MIN_10_EXP`] instead.
199///
200/// # Examples
201///
202/// ```rust
203/// // deprecated way
204/// # #[allow(deprecated, deprecated_in_future)]
205/// let min = std::f32::MIN_10_EXP;
206///
207/// // intended way
208/// let min = f32::MIN_10_EXP;
209/// ```
210#[stable(feature = "rust1", since = "1.0.0")]
211#[deprecated(since = "TBD", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
212#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
213pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
214
215/// Maximum possible power of 10 exponent.
216/// Use [`f32::MAX_10_EXP`] instead.
217///
218/// # Examples
219///
220/// ```rust
221/// // deprecated way
222/// # #[allow(deprecated, deprecated_in_future)]
223/// let max = std::f32::MAX_10_EXP;
224///
225/// // intended way
226/// let max = f32::MAX_10_EXP;
227/// ```
228#[stable(feature = "rust1", since = "1.0.0")]
229#[deprecated(since = "TBD", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
230#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
231pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
232
233/// Not a Number (NaN).
234/// Use [`f32::NAN`] instead.
235///
236/// # Examples
237///
238/// ```rust
239/// // deprecated way
240/// # #[allow(deprecated, deprecated_in_future)]
241/// let nan = std::f32::NAN;
242///
243/// // intended way
244/// let nan = f32::NAN;
245/// ```
246#[stable(feature = "rust1", since = "1.0.0")]
247#[deprecated(since = "TBD", note = "replaced by the `NAN` associated constant on `f32`")]
248#[rustc_diagnostic_item = "f32_legacy_const_nan"]
249pub const NAN: f32 = f32::NAN;
250
251/// Infinity (∞).
252/// Use [`f32::INFINITY`] instead.
253///
254/// # Examples
255///
256/// ```rust
257/// // deprecated way
258/// # #[allow(deprecated, deprecated_in_future)]
259/// let inf = std::f32::INFINITY;
260///
261/// // intended way
262/// let inf = f32::INFINITY;
263/// ```
264#[stable(feature = "rust1", since = "1.0.0")]
265#[deprecated(since = "TBD", note = "replaced by the `INFINITY` associated constant on `f32`")]
266#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
267pub const INFINITY: f32 = f32::INFINITY;
268
269/// Negative infinity (−∞).
270/// Use [`f32::NEG_INFINITY`] instead.
271///
272/// # Examples
273///
274/// ```rust
275/// // deprecated way
276/// # #[allow(deprecated, deprecated_in_future)]
277/// let ninf = std::f32::NEG_INFINITY;
278///
279/// // intended way
280/// let ninf = f32::NEG_INFINITY;
281/// ```
282#[stable(feature = "rust1", since = "1.0.0")]
283#[deprecated(since = "TBD", note = "replaced by the `NEG_INFINITY` associated constant on `f32`")]
284#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
285pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
286
287/// Basic mathematical constants.
288#[stable(feature = "rust1", since = "1.0.0")]
289#[rustc_diagnostic_item = "f32_consts_mod"]
290pub mod consts {
291 // FIXME: replace with mathematical constants from cmath.
292
293 /// Archimedes' constant (π)
294 #[stable(feature = "rust1", since = "1.0.0")]
295 pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
296
297 /// The full circle constant (τ)
298 ///
299 /// Equal to 2π.
300 #[stable(feature = "tau_constant", since = "1.47.0")]
301 pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
302
303 /// The golden ratio (φ)
304 #[unstable(feature = "more_float_constants", issue = "146939")]
305 pub const PHI: f32 = 1.618033988749894848204586834365638118_f32;
306
307 /// The Euler-Mascheroni constant (γ)
308 #[unstable(feature = "more_float_constants", issue = "146939")]
309 pub const EGAMMA: f32 = 0.577215664901532860606512090082402431_f32;
310
311 /// π/2
312 #[stable(feature = "rust1", since = "1.0.0")]
313 pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
314
315 /// π/3
316 #[stable(feature = "rust1", since = "1.0.0")]
317 pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
318
319 /// π/4
320 #[stable(feature = "rust1", since = "1.0.0")]
321 pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
322
323 /// π/6
324 #[stable(feature = "rust1", since = "1.0.0")]
325 pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
326
327 /// π/8
328 #[stable(feature = "rust1", since = "1.0.0")]
329 pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
330
331 /// 1/π
332 #[stable(feature = "rust1", since = "1.0.0")]
333 pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
334
335 /// 1/sqrt(π)
336 #[unstable(feature = "more_float_constants", issue = "146939")]
337 pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
338
339 /// 1/sqrt(2π)
340 #[doc(alias = "FRAC_1_SQRT_TAU")]
341 #[unstable(feature = "more_float_constants", issue = "146939")]
342 pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
343
344 /// 2/π
345 #[stable(feature = "rust1", since = "1.0.0")]
346 pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
347
348 /// 2/sqrt(π)
349 #[stable(feature = "rust1", since = "1.0.0")]
350 pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
351
352 /// sqrt(2)
353 #[stable(feature = "rust1", since = "1.0.0")]
354 pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
355
356 /// 1/sqrt(2)
357 #[stable(feature = "rust1", since = "1.0.0")]
358 pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
359
360 /// sqrt(3)
361 #[unstable(feature = "more_float_constants", issue = "146939")]
362 pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
363
364 /// 1/sqrt(3)
365 #[unstable(feature = "more_float_constants", issue = "146939")]
366 pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
367
368 /// Euler's number (e)
369 #[stable(feature = "rust1", since = "1.0.0")]
370 pub const E: f32 = 2.71828182845904523536028747135266250_f32;
371
372 /// log<sub>2</sub>(e)
373 #[stable(feature = "rust1", since = "1.0.0")]
374 pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
375
376 /// log<sub>2</sub>(10)
377 #[stable(feature = "extra_log_consts", since = "1.43.0")]
378 pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
379
380 /// log<sub>10</sub>(e)
381 #[stable(feature = "rust1", since = "1.0.0")]
382 pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
383
384 /// log<sub>10</sub>(2)
385 #[stable(feature = "extra_log_consts", since = "1.43.0")]
386 pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
387
388 /// ln(2)
389 #[stable(feature = "rust1", since = "1.0.0")]
390 pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
391
392 /// ln(10)
393 #[stable(feature = "rust1", since = "1.0.0")]
394 pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
395}
396
397impl f32 {
398 /// The radix or base of the internal representation of `f32`.
399 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
400 pub const RADIX: u32 = 2;
401
402 /// Number of significant digits in base 2.
403 ///
404 /// Note that the size of the mantissa in the bitwise representation is one
405 /// smaller than this since the leading 1 is not stored explicitly.
406 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
407 pub const MANTISSA_DIGITS: u32 = 24;
408
409 /// Approximate number of significant digits in base 10.
410 ///
411 /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
412 /// significant digits can be converted to `f32` and back without loss.
413 ///
414 /// Equal to floor(log<sub>10</sub> 2<sup>[`MANTISSA_DIGITS`] − 1</sup>).
415 ///
416 /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
417 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
418 pub const DIGITS: u32 = 6;
419
420 /// [Machine epsilon] value for `f32`.
421 ///
422 /// This is the difference between `1.0` and the next larger representable number.
423 ///
424 /// Equal to 2<sup>1 − [`MANTISSA_DIGITS`]</sup>.
425 ///
426 /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
427 /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
428 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
429 #[rustc_diagnostic_item = "f32_epsilon"]
430 pub const EPSILON: f32 = 1.19209290e-07_f32;
431
432 /// Smallest finite `f32` value.
433 ///
434 /// Equal to −[`MAX`].
435 ///
436 /// [`MAX`]: f32::MAX
437 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
438 pub const MIN: f32 = -3.40282347e+38_f32;
439 /// Smallest positive normal `f32` value.
440 ///
441 /// Equal to 2<sup>[`MIN_EXP`] − 1</sup>.
442 ///
443 /// [`MIN_EXP`]: f32::MIN_EXP
444 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
445 pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
446 /// Largest finite `f32` value.
447 ///
448 /// Equal to
449 /// (1 − 2<sup>−[`MANTISSA_DIGITS`]</sup>) 2<sup>[`MAX_EXP`]</sup>.
450 ///
451 /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
452 /// [`MAX_EXP`]: f32::MAX_EXP
453 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
454 pub const MAX: f32 = 3.40282347e+38_f32;
455
456 /// One greater than the minimum possible *normal* 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 minimum possible *normal* power of 2 exponent
460 /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
461 /// In other words, all normal numbers representable by this type are
462 /// greater than or equal to 0.5 × 2<sup><i>MIN_EXP</i></sup>.
463 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
464 pub const MIN_EXP: i32 = -125;
465 /// One greater than the maximum possible power of 2 exponent
466 /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
467 ///
468 /// This corresponds to the exact maximum possible power of 2 exponent
469 /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
470 /// In other words, all numbers representable by this type are
471 /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
472 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
473 pub const MAX_EXP: i32 = 128;
474
475 /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
476 ///
477 /// Equal to ceil(log<sub>10</sub> [`MIN_POSITIVE`]).
478 ///
479 /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
480 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
481 pub const MIN_10_EXP: i32 = -37;
482 /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
483 ///
484 /// Equal to floor(log<sub>10</sub> [`MAX`]).
485 ///
486 /// [`MAX`]: f32::MAX
487 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
488 pub const MAX_10_EXP: i32 = 38;
489
490 /// Not a Number (NaN).
491 ///
492 /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
493 /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
494 /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
495 /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
496 /// info.
497 ///
498 /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
499 /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
500 /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
501 /// The concrete bit pattern may change across Rust versions and target platforms.
502 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
503 #[rustc_diagnostic_item = "f32_nan"]
504 #[allow(clippy::eq_op)]
505 pub const NAN: f32 = 0.0_f32 / 0.0_f32;
506 /// Infinity (∞).
507 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
508 pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
509 /// Negative infinity (−∞).
510 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
511 pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
512
513 /// Sign bit
514 #[cfg(not(feature = "ferrocene_subset"))]
515 pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
516
517 /// Exponent mask
518 #[cfg(not(feature = "ferrocene_subset"))]
519 pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
520
521 /// Mantissa mask
522 #[cfg(not(feature = "ferrocene_subset"))]
523 pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
524
525 /// Minimum representable positive value (min subnormal)
526 #[cfg(not(feature = "ferrocene_subset"))]
527 const TINY_BITS: u32 = 0x1;
528
529 /// Minimum representable negative value (min negative subnormal)
530 #[cfg(not(feature = "ferrocene_subset"))]
531 const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
532
533 /// Returns `true` if this value is NaN.
534 ///
535 /// ```
536 /// let nan = f32::NAN;
537 /// let f = 7.0_f32;
538 ///
539 /// assert!(nan.is_nan());
540 /// assert!(!f.is_nan());
541 /// ```
542 #[must_use]
543 #[stable(feature = "rust1", since = "1.0.0")]
544 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
545 #[inline]
546 #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
547 pub const fn is_nan(self) -> bool {
548 self != self
549 }
550
551 /// Returns `true` if this value is positive infinity or negative infinity, and
552 /// `false` otherwise.
553 ///
554 /// ```
555 /// let f = 7.0f32;
556 /// let inf = f32::INFINITY;
557 /// let neg_inf = f32::NEG_INFINITY;
558 /// let nan = f32::NAN;
559 ///
560 /// assert!(!f.is_infinite());
561 /// assert!(!nan.is_infinite());
562 ///
563 /// assert!(inf.is_infinite());
564 /// assert!(neg_inf.is_infinite());
565 /// ```
566 #[must_use]
567 #[stable(feature = "rust1", since = "1.0.0")]
568 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
569 #[inline]
570 pub const fn is_infinite(self) -> bool {
571 // Getting clever with transmutation can result in incorrect answers on some FPUs
572 // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
573 // See https://github.com/rust-lang/rust/issues/72327
574 (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
575 }
576
577 /// Returns `true` if this number is neither infinite nor NaN.
578 ///
579 /// ```
580 /// let f = 7.0f32;
581 /// let inf = f32::INFINITY;
582 /// let neg_inf = f32::NEG_INFINITY;
583 /// let nan = f32::NAN;
584 ///
585 /// assert!(f.is_finite());
586 ///
587 /// assert!(!nan.is_finite());
588 /// assert!(!inf.is_finite());
589 /// assert!(!neg_inf.is_finite());
590 /// ```
591 #[must_use]
592 #[stable(feature = "rust1", since = "1.0.0")]
593 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
594 #[inline]
595 #[cfg(not(feature = "ferrocene_subset"))]
596 pub const fn is_finite(self) -> bool {
597 // There's no need to handle NaN separately: if self is NaN,
598 // the comparison is not true, exactly as desired.
599 self.abs() < Self::INFINITY
600 }
601
602 /// Returns `true` if the number is [subnormal].
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_subnormal());
611 /// assert!(!max.is_subnormal());
612 ///
613 /// assert!(!zero.is_subnormal());
614 /// assert!(!f32::NAN.is_subnormal());
615 /// assert!(!f32::INFINITY.is_subnormal());
616 /// // Values between `0` and `min` are Subnormal.
617 /// assert!(lower_than_min.is_subnormal());
618 /// ```
619 /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
620 #[must_use]
621 #[stable(feature = "is_subnormal", since = "1.53.0")]
622 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
623 #[inline]
624 #[cfg(not(feature = "ferrocene_subset"))]
625 pub const fn is_subnormal(self) -> bool {
626 matches!(self.classify(), FpCategory::Subnormal)
627 }
628
629 /// Returns `true` if the number is neither zero, infinite,
630 /// [subnormal], or NaN.
631 ///
632 /// ```
633 /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
634 /// let max = f32::MAX;
635 /// let lower_than_min = 1.0e-40_f32;
636 /// let zero = 0.0_f32;
637 ///
638 /// assert!(min.is_normal());
639 /// assert!(max.is_normal());
640 ///
641 /// assert!(!zero.is_normal());
642 /// assert!(!f32::NAN.is_normal());
643 /// assert!(!f32::INFINITY.is_normal());
644 /// // Values between `0` and `min` are Subnormal.
645 /// assert!(!lower_than_min.is_normal());
646 /// ```
647 /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
648 #[must_use]
649 #[stable(feature = "rust1", since = "1.0.0")]
650 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
651 #[inline]
652 #[cfg(not(feature = "ferrocene_subset"))]
653 pub const fn is_normal(self) -> bool {
654 matches!(self.classify(), FpCategory::Normal)
655 }
656
657 /// Returns the floating point category of the number. If only one property
658 /// is going to be tested, it is generally faster to use the specific
659 /// predicate instead.
660 ///
661 /// ```
662 /// use std::num::FpCategory;
663 ///
664 /// let num = 12.4_f32;
665 /// let inf = f32::INFINITY;
666 ///
667 /// assert_eq!(num.classify(), FpCategory::Normal);
668 /// assert_eq!(inf.classify(), FpCategory::Infinite);
669 /// ```
670 #[stable(feature = "rust1", since = "1.0.0")]
671 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
672 #[cfg(not(feature = "ferrocene_subset"))]
673 pub const fn classify(self) -> FpCategory {
674 // We used to have complicated logic here that avoids the simple bit-based tests to work
675 // around buggy codegen for x87 targets (see
676 // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
677 // of our tests is able to find any difference between the complicated and the naive
678 // version, so now we are back to the naive version.
679 let b = self.to_bits();
680 match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
681 (0, Self::EXP_MASK) => FpCategory::Infinite,
682 (_, Self::EXP_MASK) => FpCategory::Nan,
683 (0, 0) => FpCategory::Zero,
684 (_, 0) => FpCategory::Subnormal,
685 _ => FpCategory::Normal,
686 }
687 }
688
689 /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
690 /// positive sign bit and positive infinity.
691 ///
692 /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
693 /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
694 /// conserved over arithmetic operations, the result of `is_sign_positive` on
695 /// a NaN might produce an unexpected or non-portable result. See the [specification
696 /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
697 /// if you need fully portable behavior (will return `false` for all NaNs).
698 ///
699 /// ```
700 /// let f = 7.0_f32;
701 /// let g = -7.0_f32;
702 ///
703 /// assert!(f.is_sign_positive());
704 /// assert!(!g.is_sign_positive());
705 /// ```
706 #[must_use]
707 #[stable(feature = "rust1", since = "1.0.0")]
708 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
709 #[inline]
710 #[cfg(not(feature = "ferrocene_subset"))]
711 pub const fn is_sign_positive(self) -> bool {
712 !self.is_sign_negative()
713 }
714
715 /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
716 /// negative sign bit and negative infinity.
717 ///
718 /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
719 /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
720 /// conserved over arithmetic operations, the result of `is_sign_negative` on
721 /// a NaN might produce an unexpected or non-portable result. See the [specification
722 /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
723 /// if you need fully portable behavior (will return `false` for all NaNs).
724 ///
725 /// ```
726 /// let f = 7.0f32;
727 /// let g = -7.0f32;
728 ///
729 /// assert!(!f.is_sign_negative());
730 /// assert!(g.is_sign_negative());
731 /// ```
732 #[must_use]
733 #[stable(feature = "rust1", since = "1.0.0")]
734 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
735 #[inline]
736 pub const fn is_sign_negative(self) -> bool {
737 // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
738 // applies to zeros and NaNs as well.
739 self.to_bits() & 0x8000_0000 != 0
740 }
741
742 /// Returns the least number greater than `self`.
743 ///
744 /// Let `TINY` be the smallest representable positive `f32`. Then,
745 /// - if `self.is_nan()`, this returns `self`;
746 /// - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
747 /// - if `self` is `-TINY`, this returns -0.0;
748 /// - if `self` is -0.0 or +0.0, this returns `TINY`;
749 /// - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
750 /// - otherwise the unique least value greater than `self` is returned.
751 ///
752 /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
753 /// is finite `x == x.next_up().next_down()` also holds.
754 ///
755 /// ```rust
756 /// // f32::EPSILON is the difference between 1.0 and the next number up.
757 /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
758 /// // But not for most numbers.
759 /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
760 /// assert_eq!(16777216f32.next_up(), 16777218.0);
761 /// ```
762 ///
763 /// This operation corresponds to IEEE-754 `nextUp`.
764 ///
765 /// [`NEG_INFINITY`]: Self::NEG_INFINITY
766 /// [`INFINITY`]: Self::INFINITY
767 /// [`MIN`]: Self::MIN
768 /// [`MAX`]: Self::MAX
769 #[inline]
770 #[doc(alias = "nextUp")]
771 #[stable(feature = "float_next_up_down", since = "1.86.0")]
772 #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
773 #[cfg(not(feature = "ferrocene_subset"))]
774 pub const fn next_up(self) -> Self {
775 // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
776 // denormals to zero. This is in general unsound and unsupported, but here
777 // we do our best to still produce the correct result on such targets.
778 let bits = self.to_bits();
779 if self.is_nan() || bits == Self::INFINITY.to_bits() {
780 return self;
781 }
782
783 let abs = bits & !Self::SIGN_MASK;
784 let next_bits = if abs == 0 {
785 Self::TINY_BITS
786 } else if bits == abs {
787 bits + 1
788 } else {
789 bits - 1
790 };
791 Self::from_bits(next_bits)
792 }
793
794 /// Returns the greatest number less than `self`.
795 ///
796 /// Let `TINY` be the smallest representable positive `f32`. Then,
797 /// - if `self.is_nan()`, this returns `self`;
798 /// - if `self` is [`INFINITY`], this returns [`MAX`];
799 /// - if `self` is `TINY`, this returns 0.0;
800 /// - if `self` is -0.0 or +0.0, this returns `-TINY`;
801 /// - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
802 /// - otherwise the unique greatest value less than `self` is returned.
803 ///
804 /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
805 /// is finite `x == x.next_down().next_up()` also holds.
806 ///
807 /// ```rust
808 /// let x = 1.0f32;
809 /// // Clamp value into range [0, 1).
810 /// let clamped = x.clamp(0.0, 1.0f32.next_down());
811 /// assert!(clamped < 1.0);
812 /// assert_eq!(clamped.next_up(), 1.0);
813 /// ```
814 ///
815 /// This operation corresponds to IEEE-754 `nextDown`.
816 ///
817 /// [`NEG_INFINITY`]: Self::NEG_INFINITY
818 /// [`INFINITY`]: Self::INFINITY
819 /// [`MIN`]: Self::MIN
820 /// [`MAX`]: Self::MAX
821 #[inline]
822 #[doc(alias = "nextDown")]
823 #[stable(feature = "float_next_up_down", since = "1.86.0")]
824 #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
825 #[cfg(not(feature = "ferrocene_subset"))]
826 pub const fn next_down(self) -> Self {
827 // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
828 // denormals to zero. This is in general unsound and unsupported, but here
829 // we do our best to still produce the correct result on such targets.
830 let bits = self.to_bits();
831 if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
832 return self;
833 }
834
835 let abs = bits & !Self::SIGN_MASK;
836 let next_bits = if abs == 0 {
837 Self::NEG_TINY_BITS
838 } else if bits == abs {
839 bits - 1
840 } else {
841 bits + 1
842 };
843 Self::from_bits(next_bits)
844 }
845
846 /// Takes the reciprocal (inverse) of a number, `1/x`.
847 ///
848 /// ```
849 /// let x = 2.0_f32;
850 /// let abs_difference = (x.recip() - (1.0 / x)).abs();
851 ///
852 /// assert!(abs_difference <= f32::EPSILON);
853 /// ```
854 #[must_use = "this returns the result of the operation, without modifying the original"]
855 #[stable(feature = "rust1", since = "1.0.0")]
856 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
857 #[inline]
858 #[cfg(not(feature = "ferrocene_subset"))]
859 pub const fn recip(self) -> f32 {
860 1.0 / self
861 }
862
863 /// Converts radians to degrees.
864 ///
865 /// # Unspecified precision
866 ///
867 /// The precision of this function is non-deterministic. This means it varies by platform,
868 /// Rust version, and can even differ within the same execution from one invocation to the next.
869 ///
870 /// # Examples
871 ///
872 /// ```
873 /// let angle = std::f32::consts::PI;
874 ///
875 /// let abs_difference = (angle.to_degrees() - 180.0).abs();
876 /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
877 /// assert!(abs_difference <= f32::EPSILON);
878 /// ```
879 #[must_use = "this returns the result of the operation, \
880 without modifying the original"]
881 #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
882 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
883 #[inline]
884 #[cfg(not(feature = "ferrocene_subset"))]
885 pub const fn to_degrees(self) -> f32 {
886 // Use a literal to avoid double rounding, consts::PI is already rounded,
887 // and dividing would round again.
888 const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
889 self * PIS_IN_180
890 }
891
892 /// Converts degrees to radians.
893 ///
894 /// # Unspecified precision
895 ///
896 /// The precision of this function is non-deterministic. This means it varies by platform,
897 /// Rust version, and can even differ within the same execution from one invocation to the next.
898 ///
899 /// # Examples
900 ///
901 /// ```
902 /// let angle = 180.0f32;
903 ///
904 /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
905 ///
906 /// assert!(abs_difference <= f32::EPSILON);
907 /// ```
908 #[must_use = "this returns the result of the operation, \
909 without modifying the original"]
910 #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
911 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
912 #[inline]
913 #[cfg(not(feature = "ferrocene_subset"))]
914 pub const fn to_radians(self) -> f32 {
915 // The division here is correctly rounded with respect to the true value of π/180.
916 // Although π is irrational and already rounded, the double rounding happens
917 // to produce correct result for f32.
918 const RADS_PER_DEG: f32 = consts::PI / 180.0;
919 self * RADS_PER_DEG
920 }
921
922 /// Returns the maximum of the two numbers, ignoring NaN.
923 ///
924 /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
925 /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
926 /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
927 /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
928 /// non-deterministically.
929 ///
930 /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
931 /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
932 /// follows the IEEE 754-2008 semantics for `maxNum`.
933 ///
934 /// ```
935 /// let x = 1.0f32;
936 /// let y = 2.0f32;
937 ///
938 /// assert_eq!(x.max(y), y);
939 /// assert_eq!(x.max(f32::NAN), x);
940 /// ```
941 #[must_use = "this returns the result of the comparison, without modifying either input"]
942 #[stable(feature = "rust1", since = "1.0.0")]
943 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
944 #[inline]
945 pub const fn max(self, other: f32) -> f32 {
946 intrinsics::maxnumf32(self, other)
947 }
948
949 /// Returns the minimum of the two numbers, ignoring NaN.
950 ///
951 /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
952 /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
953 /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
954 /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
955 /// non-deterministically.
956 ///
957 /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
958 /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
959 /// follows the IEEE 754-2008 semantics for `minNum`.
960 ///
961 /// ```
962 /// let x = 1.0f32;
963 /// let y = 2.0f32;
964 ///
965 /// assert_eq!(x.min(y), x);
966 /// assert_eq!(x.min(f32::NAN), x);
967 /// ```
968 #[must_use = "this returns the result of the comparison, without modifying either input"]
969 #[stable(feature = "rust1", since = "1.0.0")]
970 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
971 #[inline]
972 pub const fn min(self, other: f32) -> f32 {
973 intrinsics::minnumf32(self, other)
974 }
975
976 /// Returns the maximum of the two numbers, propagating NaN.
977 ///
978 /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
979 /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
980 /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
981 /// non-NaN inputs.
982 ///
983 /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
984 /// and which does not reliably order `-0.0` and `+0.0`.
985 ///
986 /// This follows the IEEE 754-2019 semantics for `maximum`.
987 ///
988 /// ```
989 /// #![feature(float_minimum_maximum)]
990 /// let x = 1.0f32;
991 /// let y = 2.0f32;
992 ///
993 /// assert_eq!(x.maximum(y), y);
994 /// assert!(x.maximum(f32::NAN).is_nan());
995 /// ```
996 #[must_use = "this returns the result of the comparison, without modifying either input"]
997 #[unstable(feature = "float_minimum_maximum", issue = "91079")]
998 #[inline]
999 #[cfg(not(feature = "ferrocene_subset"))]
1000 pub const fn maximum(self, other: f32) -> f32 {
1001 intrinsics::maximumf32(self, other)
1002 }
1003
1004 /// Returns the minimum of the two numbers, propagating NaN.
1005 ///
1006 /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1007 /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1008 /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1009 /// non-NaN inputs.
1010 ///
1011 /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1012 /// and which does not reliably order `-0.0` and `+0.0`.
1013 ///
1014 /// This follows the IEEE 754-2019 semantics for `minimum`.
1015 ///
1016 /// ```
1017 /// #![feature(float_minimum_maximum)]
1018 /// let x = 1.0f32;
1019 /// let y = 2.0f32;
1020 ///
1021 /// assert_eq!(x.minimum(y), x);
1022 /// assert!(x.minimum(f32::NAN).is_nan());
1023 /// ```
1024 #[must_use = "this returns the result of the comparison, without modifying either input"]
1025 #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1026 #[inline]
1027 #[cfg(not(feature = "ferrocene_subset"))]
1028 pub const fn minimum(self, other: f32) -> f32 {
1029 intrinsics::minimumf32(self, other)
1030 }
1031
1032 /// Calculates the midpoint (average) between `self` and `rhs`.
1033 ///
1034 /// This returns NaN when *either* argument is NaN or if a combination of
1035 /// +inf and -inf is provided as arguments.
1036 ///
1037 /// # Examples
1038 ///
1039 /// ```
1040 /// assert_eq!(1f32.midpoint(4.0), 2.5);
1041 /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1042 /// ```
1043 #[inline]
1044 #[doc(alias = "average")]
1045 #[stable(feature = "num_midpoint", since = "1.85.0")]
1046 #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1047 #[cfg(not(feature = "ferrocene_subset"))]
1048 pub const fn midpoint(self, other: f32) -> f32 {
1049 cfg_select! {
1050 // Allow faster implementation that have known good 64-bit float
1051 // implementations. Falling back to the branchy code on targets that don't
1052 // have 64-bit hardware floats or buggy implementations.
1053 // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1054 any(
1055 target_arch = "x86_64",
1056 target_arch = "aarch64",
1057 all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1058 all(target_arch = "loongarch64", target_feature = "d"),
1059 all(target_arch = "arm", target_feature = "vfp2"),
1060 target_arch = "wasm32",
1061 target_arch = "wasm64",
1062 ) => {
1063 ((self as f64 + other as f64) / 2.0) as f32
1064 }
1065 _ => {
1066 const HI: f32 = f32::MAX / 2.;
1067
1068 let (a, b) = (self, other);
1069 let abs_a = a.abs();
1070 let abs_b = b.abs();
1071
1072 if abs_a <= HI && abs_b <= HI {
1073 // Overflow is impossible
1074 (a + b) / 2.
1075 } else {
1076 (a / 2.) + (b / 2.)
1077 }
1078 }
1079 }
1080 }
1081
1082 /// Rounds toward zero and converts to any primitive integer type,
1083 /// assuming that the value is finite and fits in that type.
1084 ///
1085 /// ```
1086 /// let value = 4.6_f32;
1087 /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1088 /// assert_eq!(rounded, 4);
1089 ///
1090 /// let value = -128.9_f32;
1091 /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1092 /// assert_eq!(rounded, i8::MIN);
1093 /// ```
1094 ///
1095 /// # Safety
1096 ///
1097 /// The value must:
1098 ///
1099 /// * Not be `NaN`
1100 /// * Not be infinite
1101 /// * Be representable in the return type `Int`, after truncating off its fractional part
1102 #[must_use = "this returns the result of the operation, \
1103 without modifying the original"]
1104 #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1105 #[inline]
1106 #[cfg(not(feature = "ferrocene_subset"))]
1107 pub unsafe fn to_int_unchecked<Int>(self) -> Int
1108 where
1109 Self: FloatToInt<Int>,
1110 {
1111 // SAFETY: the caller must uphold the safety contract for
1112 // `FloatToInt::to_int_unchecked`.
1113 unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1114 }
1115
1116 /// Raw transmutation to `u32`.
1117 ///
1118 /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1119 ///
1120 /// See [`from_bits`](Self::from_bits) for some discussion of the
1121 /// portability of this operation (there are almost no issues).
1122 ///
1123 /// Note that this function is distinct from `as` casting, which attempts to
1124 /// preserve the *numeric* value, and not the bitwise value.
1125 ///
1126 /// # Examples
1127 ///
1128 /// ```
1129 /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1130 /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1131 ///
1132 /// ```
1133 #[must_use = "this returns the result of the operation, \
1134 without modifying the original"]
1135 #[stable(feature = "float_bits_conv", since = "1.20.0")]
1136 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1137 #[inline]
1138 #[allow(unnecessary_transmutes)]
1139 pub const fn to_bits(self) -> u32 {
1140 // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1141 unsafe { mem::transmute(self) }
1142 }
1143
1144 /// Raw transmutation from `u32`.
1145 ///
1146 /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1147 /// It turns out this is incredibly portable, for two reasons:
1148 ///
1149 /// * Floats and Ints have the same endianness on all supported platforms.
1150 /// * IEEE 754 very precisely specifies the bit layout of floats.
1151 ///
1152 /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1153 /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1154 /// (notably x86 and ARM) picked the interpretation that was ultimately
1155 /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1156 /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1157 ///
1158 /// Rather than trying to preserve signaling-ness cross-platform, this
1159 /// implementation favors preserving the exact bits. This means that
1160 /// any payloads encoded in NaNs will be preserved even if the result of
1161 /// this method is sent over the network from an x86 machine to a MIPS one.
1162 ///
1163 /// If the results of this method are only manipulated by the same
1164 /// architecture that produced them, then there is no portability concern.
1165 ///
1166 /// If the input isn't NaN, then there is no portability concern.
1167 ///
1168 /// If you don't care about signalingness (very likely), then there is no
1169 /// portability concern.
1170 ///
1171 /// Note that this function is distinct from `as` casting, which attempts to
1172 /// preserve the *numeric* value, and not the bitwise value.
1173 ///
1174 /// # Examples
1175 ///
1176 /// ```
1177 /// let v = f32::from_bits(0x41480000);
1178 /// assert_eq!(v, 12.5);
1179 /// ```
1180 #[stable(feature = "float_bits_conv", since = "1.20.0")]
1181 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1182 #[must_use]
1183 #[inline]
1184 #[allow(unnecessary_transmutes)]
1185 pub const fn from_bits(v: u32) -> Self {
1186 // It turns out the safety issues with sNaN were overblown! Hooray!
1187 // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1188 unsafe { mem::transmute(v) }
1189 }
1190
1191 /// Returns the memory representation of this floating point number as a byte array in
1192 /// big-endian (network) byte order.
1193 ///
1194 /// See [`from_bits`](Self::from_bits) for some discussion of the
1195 /// portability of this operation (there are almost no issues).
1196 ///
1197 /// # Examples
1198 ///
1199 /// ```
1200 /// let bytes = 12.5f32.to_be_bytes();
1201 /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1202 /// ```
1203 #[must_use = "this returns the result of the operation, \
1204 without modifying the original"]
1205 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1206 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1207 #[inline]
1208 #[cfg(not(feature = "ferrocene_subset"))]
1209 pub const fn to_be_bytes(self) -> [u8; 4] {
1210 self.to_bits().to_be_bytes()
1211 }
1212
1213 /// Returns the memory representation of this floating point number as a byte array in
1214 /// little-endian byte order.
1215 ///
1216 /// See [`from_bits`](Self::from_bits) for some discussion of the
1217 /// portability of this operation (there are almost no issues).
1218 ///
1219 /// # Examples
1220 ///
1221 /// ```
1222 /// let bytes = 12.5f32.to_le_bytes();
1223 /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1224 /// ```
1225 #[must_use = "this returns the result of the operation, \
1226 without modifying the original"]
1227 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1228 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1229 #[inline]
1230 pub const fn to_le_bytes(self) -> [u8; 4] {
1231 self.to_bits().to_le_bytes()
1232 }
1233
1234 /// Returns the memory representation of this floating point number as a byte array in
1235 /// native byte order.
1236 ///
1237 /// As the target platform's native endianness is used, portable code
1238 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1239 ///
1240 /// [`to_be_bytes`]: f32::to_be_bytes
1241 /// [`to_le_bytes`]: f32::to_le_bytes
1242 ///
1243 /// See [`from_bits`](Self::from_bits) for some discussion of the
1244 /// portability of this operation (there are almost no issues).
1245 ///
1246 /// # Examples
1247 ///
1248 /// ```
1249 /// let bytes = 12.5f32.to_ne_bytes();
1250 /// assert_eq!(
1251 /// bytes,
1252 /// if cfg!(target_endian = "big") {
1253 /// [0x41, 0x48, 0x00, 0x00]
1254 /// } else {
1255 /// [0x00, 0x00, 0x48, 0x41]
1256 /// }
1257 /// );
1258 /// ```
1259 #[must_use = "this returns the result of the operation, \
1260 without modifying the original"]
1261 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1262 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1263 #[inline]
1264 #[cfg(not(feature = "ferrocene_subset"))]
1265 pub const fn to_ne_bytes(self) -> [u8; 4] {
1266 self.to_bits().to_ne_bytes()
1267 }
1268
1269 /// Creates a floating point value from its representation as a byte array in big endian.
1270 ///
1271 /// See [`from_bits`](Self::from_bits) for some discussion of the
1272 /// portability of this operation (there are almost no issues).
1273 ///
1274 /// # Examples
1275 ///
1276 /// ```
1277 /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
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 #[cfg(not(feature = "ferrocene_subset"))]
1285 pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1286 Self::from_bits(u32::from_be_bytes(bytes))
1287 }
1288
1289 /// Creates a floating point value from its representation as a byte array in little endian.
1290 ///
1291 /// See [`from_bits`](Self::from_bits) for some discussion of the
1292 /// portability of this operation (there are almost no issues).
1293 ///
1294 /// # Examples
1295 ///
1296 /// ```
1297 /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1298 /// assert_eq!(value, 12.5);
1299 /// ```
1300 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1301 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1302 #[must_use]
1303 #[inline]
1304 pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1305 Self::from_bits(u32::from_le_bytes(bytes))
1306 }
1307
1308 /// Creates a floating point value from its representation as a byte array in native endian.
1309 ///
1310 /// As the target platform's native endianness is used, portable code
1311 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1312 /// appropriate instead.
1313 ///
1314 /// [`from_be_bytes`]: f32::from_be_bytes
1315 /// [`from_le_bytes`]: f32::from_le_bytes
1316 ///
1317 /// See [`from_bits`](Self::from_bits) for some discussion of the
1318 /// portability of this operation (there are almost no issues).
1319 ///
1320 /// # Examples
1321 ///
1322 /// ```
1323 /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1324 /// [0x41, 0x48, 0x00, 0x00]
1325 /// } else {
1326 /// [0x00, 0x00, 0x48, 0x41]
1327 /// });
1328 /// assert_eq!(value, 12.5);
1329 /// ```
1330 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1331 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1332 #[must_use]
1333 #[inline]
1334 #[cfg(not(feature = "ferrocene_subset"))]
1335 pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1336 Self::from_bits(u32::from_ne_bytes(bytes))
1337 }
1338
1339 /// Returns the ordering between `self` and `other`.
1340 ///
1341 /// Unlike the standard partial comparison between floating point numbers,
1342 /// this comparison always produces an ordering in accordance to
1343 /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1344 /// floating point standard. The values are ordered in the following sequence:
1345 ///
1346 /// - negative quiet NaN
1347 /// - negative signaling NaN
1348 /// - negative infinity
1349 /// - negative numbers
1350 /// - negative subnormal numbers
1351 /// - negative zero
1352 /// - positive zero
1353 /// - positive subnormal numbers
1354 /// - positive numbers
1355 /// - positive infinity
1356 /// - positive signaling NaN
1357 /// - positive quiet NaN.
1358 ///
1359 /// The ordering established by this function does not always agree with the
1360 /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1361 /// they consider negative and positive zero equal, while `total_cmp`
1362 /// doesn't.
1363 ///
1364 /// The interpretation of the signaling NaN bit follows the definition in
1365 /// the IEEE 754 standard, which may not match the interpretation by some of
1366 /// the older, non-conformant (e.g. MIPS) hardware implementations.
1367 ///
1368 /// # Example
1369 ///
1370 /// ```
1371 /// struct GoodBoy {
1372 /// name: String,
1373 /// weight: f32,
1374 /// }
1375 ///
1376 /// let mut bois = vec![
1377 /// GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1378 /// GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1379 /// GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1380 /// GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1381 /// GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1382 /// GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1383 /// ];
1384 ///
1385 /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1386 ///
1387 /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1388 /// if f32::NAN.is_sign_negative() {
1389 /// assert!(bois.into_iter().map(|b| b.weight)
1390 /// .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1391 /// .all(|(a, b)| a.to_bits() == b.to_bits()))
1392 /// } else {
1393 /// assert!(bois.into_iter().map(|b| b.weight)
1394 /// .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1395 /// .all(|(a, b)| a.to_bits() == b.to_bits()))
1396 /// }
1397 /// ```
1398 #[stable(feature = "total_cmp", since = "1.62.0")]
1399 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1400 #[must_use]
1401 #[inline]
1402 #[cfg(not(feature = "ferrocene_subset"))]
1403 pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1404 let mut left = self.to_bits() as i32;
1405 let mut right = other.to_bits() as i32;
1406
1407 // In case of negatives, flip all the bits except the sign
1408 // to achieve a similar layout as two's complement integers
1409 //
1410 // Why does this work? IEEE 754 floats consist of three fields:
1411 // Sign bit, exponent and mantissa. The set of exponent and mantissa
1412 // fields as a whole have the property that their bitwise order is
1413 // equal to the numeric magnitude where the magnitude is defined.
1414 // The magnitude is not normally defined on NaN values, but
1415 // IEEE 754 totalOrder defines the NaN values also to follow the
1416 // bitwise order. This leads to order explained in the doc comment.
1417 // However, the representation of magnitude is the same for negative
1418 // and positive numbers – only the sign bit is different.
1419 // To easily compare the floats as signed integers, we need to
1420 // flip the exponent and mantissa bits in case of negative numbers.
1421 // We effectively convert the numbers to "two's complement" form.
1422 //
1423 // To do the flipping, we construct a mask and XOR against it.
1424 // We branchlessly calculate an "all-ones except for the sign bit"
1425 // mask from negative-signed values: right shifting sign-extends
1426 // the integer, so we "fill" the mask with sign bits, and then
1427 // convert to unsigned to push one more zero bit.
1428 // On positive values, the mask is all zeros, so it's a no-op.
1429 left ^= (((left >> 31) as u32) >> 1) as i32;
1430 right ^= (((right >> 31) as u32) >> 1) as i32;
1431
1432 left.cmp(&right)
1433 }
1434
1435 /// Restrict a value to a certain interval unless it is NaN.
1436 ///
1437 /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1438 /// less than `min`. Otherwise this returns `self`.
1439 ///
1440 /// Note that this function returns NaN if the initial value was NaN as
1441 /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1442 /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1443 ///
1444 /// # Panics
1445 ///
1446 /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1447 ///
1448 /// # Examples
1449 ///
1450 /// ```
1451 /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1452 /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1453 /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1454 /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1455 ///
1456 /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1457 /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1458 /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1459 /// // This is definitely a negative zero.
1460 /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1461 /// ```
1462 #[must_use = "method returns a new number and does not mutate the original value"]
1463 #[stable(feature = "clamp", since = "1.50.0")]
1464 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1465 #[inline]
1466 #[cfg(not(feature = "ferrocene_subset"))]
1467 pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1468 const_assert!(
1469 min <= max,
1470 "min > max, or either was NaN",
1471 "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1472 min: f32,
1473 max: f32,
1474 );
1475
1476 if self < min {
1477 self = min;
1478 }
1479 if self > max {
1480 self = max;
1481 }
1482 self
1483 }
1484
1485 /// Clamps this number to a symmetric range centered around zero.
1486 ///
1487 /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1488 ///
1489 /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1490 /// explicit about the intent.
1491 ///
1492 /// # Panics
1493 ///
1494 /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1495 ///
1496 /// # Examples
1497 ///
1498 /// ```
1499 /// #![feature(clamp_magnitude)]
1500 /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1501 /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1502 /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1503 /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1504 /// ```
1505 #[cfg(not(feature = "ferrocene_subset"))]
1506 #[must_use = "this returns the clamped value and does not modify the original"]
1507 #[unstable(feature = "clamp_magnitude", issue = "148519")]
1508 #[inline]
1509 pub fn clamp_magnitude(self, limit: f32) -> f32 {
1510 assert!(limit >= 0.0, "limit must be non-negative");
1511 let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1512 self.clamp(-limit, limit)
1513 }
1514
1515 /// Computes the absolute value of `self`.
1516 ///
1517 /// This function always returns the precise result.
1518 ///
1519 /// # Examples
1520 ///
1521 /// ```
1522 /// let x = 3.5_f32;
1523 /// let y = -3.5_f32;
1524 ///
1525 /// assert_eq!(x.abs(), x);
1526 /// assert_eq!(y.abs(), -y);
1527 ///
1528 /// assert!(f32::NAN.abs().is_nan());
1529 /// ```
1530 #[must_use = "method returns a new number and does not mutate the original value"]
1531 #[stable(feature = "rust1", since = "1.0.0")]
1532 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1533 #[inline]
1534 pub const fn abs(self) -> f32 {
1535 intrinsics::fabsf32(self)
1536 }
1537
1538 /// Returns a number that represents the sign of `self`.
1539 ///
1540 /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1541 /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1542 /// - NaN if the number is NaN
1543 ///
1544 /// # Examples
1545 ///
1546 /// ```
1547 /// let f = 3.5_f32;
1548 ///
1549 /// assert_eq!(f.signum(), 1.0);
1550 /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1551 ///
1552 /// assert!(f32::NAN.signum().is_nan());
1553 /// ```
1554 #[must_use = "method returns a new number and does not mutate the original value"]
1555 #[stable(feature = "rust1", since = "1.0.0")]
1556 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1557 #[inline]
1558 pub const fn signum(self) -> f32 {
1559 if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1560 }
1561
1562 /// Returns a number composed of the magnitude of `self` and the sign of
1563 /// `sign`.
1564 ///
1565 /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1566 /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1567 /// returned.
1568 ///
1569 /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1570 /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1571 /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1572 /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1573 /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1574 /// info.
1575 ///
1576 /// # Examples
1577 ///
1578 /// ```
1579 /// let f = 3.5_f32;
1580 ///
1581 /// assert_eq!(f.copysign(0.42), 3.5_f32);
1582 /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1583 /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1584 /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1585 ///
1586 /// assert!(f32::NAN.copysign(1.0).is_nan());
1587 /// ```
1588 #[must_use = "method returns a new number and does not mutate the original value"]
1589 #[inline]
1590 #[stable(feature = "copysign", since = "1.35.0")]
1591 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1592 pub const fn copysign(self, sign: f32) -> f32 {
1593 intrinsics::copysignf32(self, sign)
1594 }
1595
1596 /// Float addition that allows optimizations based on algebraic rules.
1597 ///
1598 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1599 #[must_use = "method returns a new number and does not mutate the original value"]
1600 #[unstable(feature = "float_algebraic", issue = "136469")]
1601 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1602 #[inline]
1603 #[cfg(not(feature = "ferrocene_subset"))]
1604 pub const fn algebraic_add(self, rhs: f32) -> f32 {
1605 intrinsics::fadd_algebraic(self, rhs)
1606 }
1607
1608 /// Float subtraction that allows optimizations based on algebraic rules.
1609 ///
1610 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1611 #[must_use = "method returns a new number and does not mutate the original value"]
1612 #[unstable(feature = "float_algebraic", issue = "136469")]
1613 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1614 #[inline]
1615 #[cfg(not(feature = "ferrocene_subset"))]
1616 pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1617 intrinsics::fsub_algebraic(self, rhs)
1618 }
1619
1620 /// Float multiplication that allows optimizations based on algebraic rules.
1621 ///
1622 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1623 #[must_use = "method returns a new number and does not mutate the original value"]
1624 #[unstable(feature = "float_algebraic", issue = "136469")]
1625 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1626 #[inline]
1627 #[cfg(not(feature = "ferrocene_subset"))]
1628 pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1629 intrinsics::fmul_algebraic(self, rhs)
1630 }
1631
1632 /// Float division that allows optimizations based on algebraic rules.
1633 ///
1634 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1635 #[must_use = "method returns a new number and does not mutate the original value"]
1636 #[unstable(feature = "float_algebraic", issue = "136469")]
1637 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1638 #[inline]
1639 #[cfg(not(feature = "ferrocene_subset"))]
1640 pub const fn algebraic_div(self, rhs: f32) -> f32 {
1641 intrinsics::fdiv_algebraic(self, rhs)
1642 }
1643
1644 /// Float remainder that allows optimizations based on algebraic rules.
1645 ///
1646 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1647 #[must_use = "method returns a new number and does not mutate the original value"]
1648 #[unstable(feature = "float_algebraic", issue = "136469")]
1649 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1650 #[inline]
1651 #[cfg(not(feature = "ferrocene_subset"))]
1652 pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1653 intrinsics::frem_algebraic(self, rhs)
1654 }
1655}
1656
1657/// Experimental implementations of floating point functions in `core`.
1658///
1659/// _The standalone functions in this module are for testing only.
1660/// They will be stabilized as inherent methods._
1661#[unstable(feature = "core_float_math", issue = "137578")]
1662#[cfg(not(feature = "ferrocene_subset"))]
1663pub mod math {
1664 use crate::intrinsics;
1665 use crate::num::libm;
1666
1667 /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1668 ///
1669 /// # Examples
1670 ///
1671 /// ```
1672 /// #![feature(core_float_math)]
1673 ///
1674 /// use core::f32;
1675 ///
1676 /// let f = 3.7_f32;
1677 /// let g = 3.0_f32;
1678 /// let h = -3.7_f32;
1679 ///
1680 /// assert_eq!(f32::math::floor(f), 3.0);
1681 /// assert_eq!(f32::math::floor(g), 3.0);
1682 /// assert_eq!(f32::math::floor(h), -4.0);
1683 /// ```
1684 ///
1685 /// _This standalone function is for testing only.
1686 /// It will be stabilized as an inherent method._
1687 ///
1688 /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1689 #[inline]
1690 #[unstable(feature = "core_float_math", issue = "137578")]
1691 #[must_use = "method returns a new number and does not mutate the original value"]
1692 pub const fn floor(x: f32) -> f32 {
1693 intrinsics::floorf32(x)
1694 }
1695
1696 /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1697 ///
1698 /// # Examples
1699 ///
1700 /// ```
1701 /// #![feature(core_float_math)]
1702 ///
1703 /// use core::f32;
1704 ///
1705 /// let f = 3.01_f32;
1706 /// let g = 4.0_f32;
1707 ///
1708 /// assert_eq!(f32::math::ceil(f), 4.0);
1709 /// assert_eq!(f32::math::ceil(g), 4.0);
1710 /// ```
1711 ///
1712 /// _This standalone function is for testing only.
1713 /// It will be stabilized as an inherent method._
1714 ///
1715 /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1716 #[inline]
1717 #[doc(alias = "ceiling")]
1718 #[must_use = "method returns a new number and does not mutate the original value"]
1719 #[unstable(feature = "core_float_math", issue = "137578")]
1720 pub const fn ceil(x: f32) -> f32 {
1721 intrinsics::ceilf32(x)
1722 }
1723
1724 /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1725 ///
1726 /// # Examples
1727 ///
1728 /// ```
1729 /// #![feature(core_float_math)]
1730 ///
1731 /// use core::f32;
1732 ///
1733 /// let f = 3.3_f32;
1734 /// let g = -3.3_f32;
1735 /// let h = -3.7_f32;
1736 /// let i = 3.5_f32;
1737 /// let j = 4.5_f32;
1738 ///
1739 /// assert_eq!(f32::math::round(f), 3.0);
1740 /// assert_eq!(f32::math::round(g), -3.0);
1741 /// assert_eq!(f32::math::round(h), -4.0);
1742 /// assert_eq!(f32::math::round(i), 4.0);
1743 /// assert_eq!(f32::math::round(j), 5.0);
1744 /// ```
1745 ///
1746 /// _This standalone function is for testing only.
1747 /// It will be stabilized as an inherent method._
1748 ///
1749 /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1750 #[inline]
1751 #[unstable(feature = "core_float_math", issue = "137578")]
1752 #[must_use = "method returns a new number and does not mutate the original value"]
1753 pub const fn round(x: f32) -> f32 {
1754 intrinsics::roundf32(x)
1755 }
1756
1757 /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1758 /// details.
1759 ///
1760 /// # Examples
1761 ///
1762 /// ```
1763 /// #![feature(core_float_math)]
1764 ///
1765 /// use core::f32;
1766 ///
1767 /// let f = 3.3_f32;
1768 /// let g = -3.3_f32;
1769 /// let h = 3.5_f32;
1770 /// let i = 4.5_f32;
1771 ///
1772 /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1773 /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1774 /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1775 /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1776 /// ```
1777 ///
1778 /// _This standalone function is for testing only.
1779 /// It will be stabilized as an inherent method._
1780 ///
1781 /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1782 #[inline]
1783 #[unstable(feature = "core_float_math", issue = "137578")]
1784 #[must_use = "method returns a new number and does not mutate the original value"]
1785 pub const fn round_ties_even(x: f32) -> f32 {
1786 intrinsics::round_ties_even_f32(x)
1787 }
1788
1789 /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1790 ///
1791 /// # Examples
1792 ///
1793 /// ```
1794 /// #![feature(core_float_math)]
1795 ///
1796 /// use core::f32;
1797 ///
1798 /// let f = 3.7_f32;
1799 /// let g = 3.0_f32;
1800 /// let h = -3.7_f32;
1801 ///
1802 /// assert_eq!(f32::math::trunc(f), 3.0);
1803 /// assert_eq!(f32::math::trunc(g), 3.0);
1804 /// assert_eq!(f32::math::trunc(h), -3.0);
1805 /// ```
1806 ///
1807 /// _This standalone function is for testing only.
1808 /// It will be stabilized as an inherent method._
1809 ///
1810 /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1811 #[inline]
1812 #[doc(alias = "truncate")]
1813 #[must_use = "method returns a new number and does not mutate the original value"]
1814 #[unstable(feature = "core_float_math", issue = "137578")]
1815 pub const fn trunc(x: f32) -> f32 {
1816 intrinsics::truncf32(x)
1817 }
1818
1819 /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1820 ///
1821 /// # Examples
1822 ///
1823 /// ```
1824 /// #![feature(core_float_math)]
1825 ///
1826 /// use core::f32;
1827 ///
1828 /// let x = 3.6_f32;
1829 /// let y = -3.6_f32;
1830 /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1831 /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1832 ///
1833 /// assert!(abs_difference_x <= f32::EPSILON);
1834 /// assert!(abs_difference_y <= f32::EPSILON);
1835 /// ```
1836 ///
1837 /// _This standalone function is for testing only.
1838 /// It will be stabilized as an inherent method._
1839 ///
1840 /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1841 #[inline]
1842 #[unstable(feature = "core_float_math", issue = "137578")]
1843 #[must_use = "method returns a new number and does not mutate the original value"]
1844 pub const fn fract(x: f32) -> f32 {
1845 x - trunc(x)
1846 }
1847
1848 /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1849 ///
1850 /// # Examples
1851 ///
1852 /// ```
1853 /// #![feature(core_float_math)]
1854 ///
1855 /// # // FIXME(#140515): mingw has an incorrect fma
1856 /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1857 /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1858 /// use core::f32;
1859 ///
1860 /// let m = 10.0_f32;
1861 /// let x = 4.0_f32;
1862 /// let b = 60.0_f32;
1863 ///
1864 /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1865 /// assert_eq!(m * x + b, 100.0);
1866 ///
1867 /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1868 /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1869 /// let minus_one = -1.0_f32;
1870 ///
1871 /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1872 /// assert_eq!(
1873 /// f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1874 /// -f32::EPSILON * f32::EPSILON
1875 /// );
1876 /// // Different rounding with the non-fused multiply and add.
1877 /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1878 /// # }
1879 /// ```
1880 ///
1881 /// _This standalone function is for testing only.
1882 /// It will be stabilized as an inherent method._
1883 ///
1884 /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1885 #[inline]
1886 #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1887 #[must_use = "method returns a new number and does not mutate the original value"]
1888 #[unstable(feature = "core_float_math", issue = "137578")]
1889 pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1890 intrinsics::fmaf32(x, y, z)
1891 }
1892
1893 /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1894 ///
1895 /// # Examples
1896 ///
1897 /// ```
1898 /// #![feature(core_float_math)]
1899 ///
1900 /// use core::f32;
1901 ///
1902 /// let a: f32 = 7.0;
1903 /// let b = 4.0;
1904 /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1905 /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1906 /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1907 /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1908 /// ```
1909 ///
1910 /// _This standalone function is for testing only.
1911 /// It will be stabilized as an inherent method._
1912 ///
1913 /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
1914 #[inline]
1915 #[unstable(feature = "core_float_math", issue = "137578")]
1916 #[must_use = "method returns a new number and does not mutate the original value"]
1917 pub fn div_euclid(x: f32, rhs: f32) -> f32 {
1918 let q = trunc(x / rhs);
1919 if x % rhs < 0.0 {
1920 return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
1921 }
1922 q
1923 }
1924
1925 /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
1926 ///
1927 /// # Examples
1928 ///
1929 /// ```
1930 /// #![feature(core_float_math)]
1931 ///
1932 /// use core::f32;
1933 ///
1934 /// let a: f32 = 7.0;
1935 /// let b = 4.0;
1936 /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
1937 /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
1938 /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
1939 /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
1940 /// // limitation due to round-off error
1941 /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
1942 /// ```
1943 ///
1944 /// _This standalone function is for testing only.
1945 /// It will be stabilized as an inherent method._
1946 ///
1947 /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
1948 #[inline]
1949 #[doc(alias = "modulo", alias = "mod")]
1950 #[unstable(feature = "core_float_math", issue = "137578")]
1951 #[must_use = "method returns a new number and does not mutate the original value"]
1952 pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
1953 let r = x % rhs;
1954 if r < 0.0 { r + rhs.abs() } else { r }
1955 }
1956
1957 /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
1958 ///
1959 /// # Examples
1960 ///
1961 /// ```
1962 /// #![feature(core_float_math)]
1963 ///
1964 /// use core::f32;
1965 ///
1966 /// let x = 2.0_f32;
1967 /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
1968 /// assert!(abs_difference <= 1e-5);
1969 ///
1970 /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
1971 /// ```
1972 ///
1973 /// _This standalone function is for testing only.
1974 /// It will be stabilized as an inherent method._
1975 ///
1976 /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
1977 #[inline]
1978 #[must_use = "method returns a new number and does not mutate the original value"]
1979 #[unstable(feature = "core_float_math", issue = "137578")]
1980 pub fn powi(x: f32, n: i32) -> f32 {
1981 intrinsics::powif32(x, n)
1982 }
1983
1984 /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
1985 ///
1986 /// # Examples
1987 ///
1988 /// ```
1989 /// #![feature(core_float_math)]
1990 ///
1991 /// use core::f32;
1992 ///
1993 /// let positive = 4.0_f32;
1994 /// let negative = -4.0_f32;
1995 /// let negative_zero = -0.0_f32;
1996 ///
1997 /// assert_eq!(f32::math::sqrt(positive), 2.0);
1998 /// assert!(f32::math::sqrt(negative).is_nan());
1999 /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2000 /// ```
2001 ///
2002 /// _This standalone function is for testing only.
2003 /// It will be stabilized as an inherent method._
2004 ///
2005 /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2006 #[inline]
2007 #[doc(alias = "squareRoot")]
2008 #[unstable(feature = "core_float_math", issue = "137578")]
2009 #[must_use = "method returns a new number and does not mutate the original value"]
2010 pub fn sqrt(x: f32) -> f32 {
2011 intrinsics::sqrtf32(x)
2012 }
2013
2014 /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2015 ///
2016 /// # Examples
2017 ///
2018 /// ```
2019 /// #![feature(core_float_math)]
2020 ///
2021 /// use core::f32;
2022 ///
2023 /// let x = 3.0f32;
2024 /// let y = -3.0f32;
2025 ///
2026 /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2027 /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2028 ///
2029 /// assert!(abs_difference_x <= 1e-6);
2030 /// assert!(abs_difference_y <= 1e-6);
2031 /// ```
2032 ///
2033 /// _This standalone function is for testing only.
2034 /// It will be stabilized as an inherent method._
2035 ///
2036 /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2037 #[inline]
2038 #[stable(feature = "rust1", since = "1.0.0")]
2039 #[deprecated(
2040 since = "1.10.0",
2041 note = "you probably meant `(self - other).abs()`: \
2042 this operation is `(self - other).max(0.0)` \
2043 except that `abs_sub` also propagates NaNs (also \
2044 known as `fdimf` in C). If you truly need the positive \
2045 difference, consider using that expression or the C function \
2046 `fdimf`, depending on how you wish to handle NaN (please consider \
2047 filing an issue describing your use-case too)."
2048 )]
2049 #[must_use = "method returns a new number and does not mutate the original value"]
2050 pub fn abs_sub(x: f32, other: f32) -> f32 {
2051 libm::fdimf(x, other)
2052 }
2053
2054 /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2055 ///
2056 /// # Unspecified precision
2057 ///
2058 /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2059 /// can even differ within the same execution from one invocation to the next.
2060 /// This function currently corresponds to the `cbrtf` from libc on Unix
2061 /// and Windows. Note that this might change in the future.
2062 ///
2063 /// # Examples
2064 ///
2065 /// ```
2066 /// #![feature(core_float_math)]
2067 ///
2068 /// use core::f32;
2069 ///
2070 /// let x = 8.0f32;
2071 ///
2072 /// // x^(1/3) - 2 == 0
2073 /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2074 ///
2075 /// assert!(abs_difference <= 1e-6);
2076 /// ```
2077 ///
2078 /// _This standalone function is for testing only.
2079 /// It will be stabilized as an inherent method._
2080 ///
2081 /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2082 #[inline]
2083 #[must_use = "method returns a new number and does not mutate the original value"]
2084 #[unstable(feature = "core_float_math", issue = "137578")]
2085 pub fn cbrt(x: f32) -> f32 {
2086 libm::cbrtf(x)
2087 }
2088}