Trait num::traits::Float
[-] [+]
[src]
pub trait Float: Num + Copy + NumCast + PartialOrd + Neg<Output=Self> {
fn nan() -> Self;
fn infinity() -> Self;
fn neg_infinity() -> Self;
fn neg_zero() -> Self;
fn min_value() -> Self;
fn max_value() -> Self;
fn is_nan(self) -> bool;
fn is_infinite(self) -> bool;
fn is_finite(self) -> bool;
fn is_normal(self) -> bool;
fn classify(self) -> FpCategory;
fn floor(self) -> Self;
fn ceil(self) -> Self;
fn round(self) -> Self;
fn trunc(self) -> Self;
fn fract(self) -> Self;
fn abs(self) -> Self;
fn signum(self) -> Self;
fn is_sign_positive(self) -> bool;
fn is_sign_negative(self) -> bool;
fn mul_add(self, a: Self, b: Self) -> Self;
fn recip(self) -> Self;
fn powi(self, n: i32) -> Self;
fn powf(self, n: Self) -> Self;
fn sqrt(self) -> Self;
fn exp(self) -> Self;
fn exp2(self) -> Self;
fn ln(self) -> Self;
fn log(self, base: Self) -> Self;
fn log2(self) -> Self;
fn log10(self) -> Self;
fn max(self, other: Self) -> Self;
fn min(self, other: Self) -> Self;
fn abs_sub(self, other: Self) -> Self;
fn cbrt(self) -> Self;
fn hypot(self, other: Self) -> Self;
fn sin(self) -> Self;
fn cos(self) -> Self;
fn tan(self) -> Self;
fn asin(self) -> Self;
fn acos(self) -> Self;
fn atan(self) -> Self;
fn atan2(self, other: Self) -> Self;
fn sin_cos(self) -> (Self, Self);
fn exp_m1(self) -> Self;
fn ln_1p(self) -> Self;
fn sinh(self) -> Self;
fn cosh(self) -> Self;
fn tanh(self) -> Self;
fn asinh(self) -> Self;
fn acosh(self) -> Self;
fn atanh(self) -> Self;
fn integer_decode(self) -> (u64, i16, i8);
}
Required Methods
fn nan() -> Self
Returns the NaN value.
use num::traits::Float; let nan: f32 = Float::nan(); assert!(nan.is_nan());
fn infinity() -> Self
Returns the infinite value.
extern crate num; fn main() { use num::traits::Float; use std::f32; let infinity: f32 = Float::infinity(); assert!(infinity.is_infinite()); assert!(!infinity.is_finite()); assert!(infinity > f32::MAX); }use num::traits::Float; use std::f32; let infinity: f32 = Float::infinity(); assert!(infinity.is_infinite()); assert!(!infinity.is_finite()); assert!(infinity > f32::MAX);
fn neg_infinity() -> Self
Returns the negative infinite value.
extern crate num; fn main() { use num::traits::Float; use std::f32; let neg_infinity: f32 = Float::neg_infinity(); assert!(neg_infinity.is_infinite()); assert!(!neg_infinity.is_finite()); assert!(neg_infinity < f32::MIN); }use num::traits::Float; use std::f32; let neg_infinity: f32 = Float::neg_infinity(); assert!(neg_infinity.is_infinite()); assert!(!neg_infinity.is_finite()); assert!(neg_infinity < f32::MIN);
fn neg_zero() -> Self
Returns -0.0.
use num::traits::{Zero, Float}; let inf: f32 = Float::infinity(); let zero: f32 = Zero::zero(); let neg_zero: f32 = Float::neg_zero(); assert_eq!(zero, neg_zero); assert_eq!(7.0f32/inf, zero); assert_eq!(zero * 10.0, zero);
fn min_value() -> Self
Returns the smallest finite value that this type can represent.
extern crate num; fn main() { use num::traits::Float; use std::f64; let x: f64 = Float::min_value(); assert_eq!(x, f64::MIN); }use num::traits::Float; use std::f64; let x: f64 = Float::min_value(); assert_eq!(x, f64::MIN);
fn max_value() -> Self
Returns the largest finite value that this type can represent.
extern crate num; fn main() { use num::traits::Float; use std::f64; let x: f64 = Float::max_value(); assert_eq!(x, f64::MAX); }use num::traits::Float; use std::f64; let x: f64 = Float::max_value(); assert_eq!(x, f64::MAX);
fn is_nan(self) -> bool
Returns true if this value is NaN and false otherwise.
use num::traits::Float; use std::f64; let nan = f64::NAN; let f = 7.0; assert!(nan.is_nan()); assert!(!f.is_nan());
fn is_infinite(self) -> bool
Returns true if this value is positive infinity or negative infinity and
false otherwise.
use num::traits::Float; use std::f32; let f = 7.0f32; let inf: f32 = Float::infinity(); let neg_inf: f32 = Float::neg_infinity(); let nan: f32 = f32::NAN; assert!(!f.is_infinite()); assert!(!nan.is_infinite()); assert!(inf.is_infinite()); assert!(neg_inf.is_infinite());
fn is_finite(self) -> bool
Returns true if this number is neither infinite nor NaN.
use num::traits::Float; use std::f32; let f = 7.0f32; let inf: f32 = Float::infinity(); let neg_inf: f32 = Float::neg_infinity(); let nan: f32 = f32::NAN; assert!(f.is_finite()); assert!(!nan.is_finite()); assert!(!inf.is_finite()); assert!(!neg_inf.is_finite());
fn is_normal(self) -> bool
Returns true if the number is neither zero, infinite,
subnormal, or NaN.
use num::traits::Float; use std::f32; let min = f32::MIN_POSITIVE; // 1.17549435e-38f32 let max = f32::MAX; let lower_than_min = 1.0e-40_f32; let zero = 0.0f32; assert!(min.is_normal()); assert!(max.is_normal()); assert!(!zero.is_normal()); assert!(!f32::NAN.is_normal()); assert!(!f32::INFINITY.is_normal()); // Values between `0` and `min` are Subnormal. assert!(!lower_than_min.is_normal());
fn classify(self) -> FpCategory
Returns the floating point category of the number. If only one property is going to be tested, it is generally faster to use the specific predicate instead.
extern crate num; fn main() { use num::traits::Float; use std::num::FpCategory; use std::f32; let num = 12.4f32; let inf = f32::INFINITY; assert_eq!(num.classify(), FpCategory::Normal); assert_eq!(inf.classify(), FpCategory::Infinite); }use num::traits::Float; use std::num::FpCategory; use std::f32; let num = 12.4f32; let inf = f32::INFINITY; assert_eq!(num.classify(), FpCategory::Normal); assert_eq!(inf.classify(), FpCategory::Infinite);
fn floor(self) -> Self
Returns the largest integer less than or equal to a number.
extern crate num; fn main() { use num::traits::Float; let f = 3.99; let g = 3.0; assert_eq!(f.floor(), 3.0); assert_eq!(g.floor(), 3.0); }use num::traits::Float; let f = 3.99; let g = 3.0; assert_eq!(f.floor(), 3.0); assert_eq!(g.floor(), 3.0);
fn ceil(self) -> Self
Returns the smallest integer greater than or equal to a number.
extern crate num; fn main() { use num::traits::Float; let f = 3.01; let g = 4.0; assert_eq!(f.ceil(), 4.0); assert_eq!(g.ceil(), 4.0); }use num::traits::Float; let f = 3.01; let g = 4.0; assert_eq!(f.ceil(), 4.0); assert_eq!(g.ceil(), 4.0);
fn round(self) -> Self
Returns the nearest integer to a number. Round half-way cases away from
0.0.
use num::traits::Float; let f = 3.3; let g = -3.3; assert_eq!(f.round(), 3.0); assert_eq!(g.round(), -3.0);
fn trunc(self) -> Self
Return the integer part of a number.
extern crate num; fn main() { use num::traits::Float; let f = 3.3; let g = -3.7; assert_eq!(f.trunc(), 3.0); assert_eq!(g.trunc(), -3.0); }use num::traits::Float; let f = 3.3; let g = -3.7; assert_eq!(f.trunc(), 3.0); assert_eq!(g.trunc(), -3.0);
fn fract(self) -> Self
Returns the fractional part of a number.
extern crate num; fn main() { use num::traits::Float; let x = 3.5; let y = -3.5; let abs_difference_x = (x.fract() - 0.5).abs(); let abs_difference_y = (y.fract() - (-0.5)).abs(); assert!(abs_difference_x < 1e-10); assert!(abs_difference_y < 1e-10); }use num::traits::Float; let x = 3.5; let y = -3.5; let abs_difference_x = (x.fract() - 0.5).abs(); let abs_difference_y = (y.fract() - (-0.5)).abs(); assert!(abs_difference_x < 1e-10); assert!(abs_difference_y < 1e-10);
fn abs(self) -> Self
Computes the absolute value of self. Returns Float::nan() if the
number is Float::nan().
use num::traits::Float; use std::f64; let x = 3.5; let y = -3.5; let abs_difference_x = (x.abs() - x).abs(); let abs_difference_y = (y.abs() - (-y)).abs(); assert!(abs_difference_x < 1e-10); assert!(abs_difference_y < 1e-10); assert!(f64::NAN.abs().is_nan());
fn signum(self) -> Self
Returns a number that represents the sign of self.
1.0if the number is positive,+0.0orFloat::infinity()-1.0if the number is negative,-0.0orFloat::neg_infinity()Float::nan()if the number isFloat::nan()
use num::traits::Float; use std::f64; let f = 3.5; assert_eq!(f.signum(), 1.0); assert_eq!(f64::NEG_INFINITY.signum(), -1.0); assert!(f64::NAN.signum().is_nan());
fn is_sign_positive(self) -> bool
Returns true if self is positive, including +0.0 and
Float::infinity().
use num::traits::Float; use std::f64; let nan: f64 = f64::NAN; let f = 7.0; let g = -7.0; assert!(f.is_sign_positive()); assert!(!g.is_sign_positive()); // Requires both tests to determine if is `NaN` assert!(!nan.is_sign_positive() && !nan.is_sign_negative());
fn is_sign_negative(self) -> bool
Returns true if self is negative, including -0.0 and
Float::neg_infinity().
use num::traits::Float; use std::f64; let nan = f64::NAN; let f = 7.0; let g = -7.0; assert!(!f.is_sign_negative()); assert!(g.is_sign_negative()); // Requires both tests to determine if is `NaN`. assert!(!nan.is_sign_positive() && !nan.is_sign_negative());
fn mul_add(self, a: Self, b: Self) -> Self
Fused multiply-add. Computes (self * a) + b with only one rounding
error. This produces a more accurate result with better performance than
a separate multiplication operation followed by an add.
use num::traits::Float; let m = 10.0; let x = 4.0; let b = 60.0; // 100.0 let abs_difference = (m.mul_add(x, b) - (m*x + b)).abs(); assert!(abs_difference < 1e-10);
fn recip(self) -> Self
Take the reciprocal (inverse) of a number, 1/x.
use num::traits::Float; let x = 2.0; let abs_difference = (x.recip() - (1.0/x)).abs(); assert!(abs_difference < 1e-10);
fn powi(self, n: i32) -> Self
Raise a number to an integer power.
Using this function is generally faster than using powf
use num::traits::Float; let x = 2.0; let abs_difference = (x.powi(2) - x*x).abs(); assert!(abs_difference < 1e-10);
fn powf(self, n: Self) -> Self
Raise a number to a floating point power.
extern crate num; fn main() { use num::traits::Float; let x = 2.0; let abs_difference = (x.powf(2.0) - x*x).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; let x = 2.0; let abs_difference = (x.powf(2.0) - x*x).abs(); assert!(abs_difference < 1e-10);
fn sqrt(self) -> Self
Take the square root of a number.
Returns NaN if self is a negative number.
use num::traits::Float; let positive = 4.0; let negative = -4.0; let abs_difference = (positive.sqrt() - 2.0).abs(); assert!(abs_difference < 1e-10); assert!(negative.sqrt().is_nan());
fn exp(self) -> Self
Returns e^(self), (the exponential function).
use num::traits::Float; let one = 1.0; // e^1 let e = one.exp(); // ln(e) - 1 == 0 let abs_difference = (e.ln() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn exp2(self) -> Self
Returns 2^(self).
use num::traits::Float; let f = 2.0; // 2^2 - 4 == 0 let abs_difference = (f.exp2() - 4.0).abs(); assert!(abs_difference < 1e-10);
fn ln(self) -> Self
Returns the natural logarithm of the number.
extern crate num; fn main() { use num::traits::Float; let one = 1.0; // e^1 let e = one.exp(); // ln(e) - 1 == 0 let abs_difference = (e.ln() - 1.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; let one = 1.0; // e^1 let e = one.exp(); // ln(e) - 1 == 0 let abs_difference = (e.ln() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn log(self, base: Self) -> Self
Returns the logarithm of the number with respect to an arbitrary base.
extern crate num; fn main() { use num::traits::Float; let ten = 10.0; let two = 2.0; // log10(10) - 1 == 0 let abs_difference_10 = (ten.log(10.0) - 1.0).abs(); // log2(2) - 1 == 0 let abs_difference_2 = (two.log(2.0) - 1.0).abs(); assert!(abs_difference_10 < 1e-10); assert!(abs_difference_2 < 1e-10); }use num::traits::Float; let ten = 10.0; let two = 2.0; // log10(10) - 1 == 0 let abs_difference_10 = (ten.log(10.0) - 1.0).abs(); // log2(2) - 1 == 0 let abs_difference_2 = (two.log(2.0) - 1.0).abs(); assert!(abs_difference_10 < 1e-10); assert!(abs_difference_2 < 1e-10);
fn log2(self) -> Self
Returns the base 2 logarithm of the number.
extern crate num; fn main() { use num::traits::Float; let two = 2.0; // log2(2) - 1 == 0 let abs_difference = (two.log2() - 1.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; let two = 2.0; // log2(2) - 1 == 0 let abs_difference = (two.log2() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn log10(self) -> Self
Returns the base 10 logarithm of the number.
extern crate num; fn main() { use num::traits::Float; let ten = 10.0; // log10(10) - 1 == 0 let abs_difference = (ten.log10() - 1.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; let ten = 10.0; // log10(10) - 1 == 0 let abs_difference = (ten.log10() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn max(self, other: Self) -> Self
Returns the maximum of the two numbers.
extern crate num; fn main() { use num::traits::Float; let x = 1.0; let y = 2.0; assert_eq!(x.max(y), y); }use num::traits::Float; let x = 1.0; let y = 2.0; assert_eq!(x.max(y), y);
fn min(self, other: Self) -> Self
Returns the minimum of the two numbers.
extern crate num; fn main() { use num::traits::Float; let x = 1.0; let y = 2.0; assert_eq!(x.min(y), x); }use num::traits::Float; let x = 1.0; let y = 2.0; assert_eq!(x.min(y), x);
fn abs_sub(self, other: Self) -> Self
The positive difference of two numbers.
- If
self <= other:0:0 - Else:
self - other
use num::traits::Float; let x = 3.0; let y = -3.0; let abs_difference_x = (x.abs_sub(1.0) - 2.0).abs(); let abs_difference_y = (y.abs_sub(1.0) - 0.0).abs(); assert!(abs_difference_x < 1e-10); assert!(abs_difference_y < 1e-10);
fn cbrt(self) -> Self
Take the cubic root of a number.
extern crate num; fn main() { use num::traits::Float; let x = 8.0; // x^(1/3) - 2 == 0 let abs_difference = (x.cbrt() - 2.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; let x = 8.0; // x^(1/3) - 2 == 0 let abs_difference = (x.cbrt() - 2.0).abs(); assert!(abs_difference < 1e-10);
fn hypot(self, other: Self) -> Self
Calculate the length of the hypotenuse of a right-angle triangle given
legs of length x and y.
use num::traits::Float; let x = 2.0; let y = 3.0; // sqrt(x^2 + y^2) let abs_difference = (x.hypot(y) - (x.powi(2) + y.powi(2)).sqrt()).abs(); assert!(abs_difference < 1e-10);
fn sin(self) -> Self
Computes the sine of a number (in radians).
extern crate num; fn main() { use num::traits::Float; use std::f64; let x = f64::consts::PI/2.0; let abs_difference = (x.sin() - 1.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; use std::f64; let x = f64::consts::PI/2.0; let abs_difference = (x.sin() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn cos(self) -> Self
Computes the cosine of a number (in radians).
extern crate num; fn main() { use num::traits::Float; use std::f64; let x = 2.0*f64::consts::PI; let abs_difference = (x.cos() - 1.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; use std::f64; let x = 2.0*f64::consts::PI; let abs_difference = (x.cos() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn tan(self) -> Self
Computes the tangent of a number (in radians).
extern crate num; fn main() { use num::traits::Float; use std::f64; let x = f64::consts::PI/4.0; let abs_difference = (x.tan() - 1.0).abs(); assert!(abs_difference < 1e-14); }use num::traits::Float; use std::f64; let x = f64::consts::PI/4.0; let abs_difference = (x.tan() - 1.0).abs(); assert!(abs_difference < 1e-14);
fn asin(self) -> Self
Computes the arcsine of a number. Return value is in radians in the range [-pi/2, pi/2] or NaN if the number is outside the range [-1, 1].
extern crate num; fn main() { use num::traits::Float; use std::f64; let f = f64::consts::PI / 2.0; // asin(sin(pi/2)) let abs_difference = (f.sin().asin() - f64::consts::PI / 2.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; use std::f64; let f = f64::consts::PI / 2.0; // asin(sin(pi/2)) let abs_difference = (f.sin().asin() - f64::consts::PI / 2.0).abs(); assert!(abs_difference < 1e-10);
fn acos(self) -> Self
Computes the arccosine of a number. Return value is in radians in the range [0, pi] or NaN if the number is outside the range [-1, 1].
extern crate num; fn main() { use num::traits::Float; use std::f64; let f = f64::consts::PI / 4.0; // acos(cos(pi/4)) let abs_difference = (f.cos().acos() - f64::consts::PI / 4.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; use std::f64; let f = f64::consts::PI / 4.0; // acos(cos(pi/4)) let abs_difference = (f.cos().acos() - f64::consts::PI / 4.0).abs(); assert!(abs_difference < 1e-10);
fn atan(self) -> Self
Computes the arctangent of a number. Return value is in radians in the range [-pi/2, pi/2];
extern crate num; fn main() { use num::traits::Float; let f = 1.0; // atan(tan(1)) let abs_difference = (f.tan().atan() - 1.0).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; let f = 1.0; // atan(tan(1)) let abs_difference = (f.tan().atan() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn atan2(self, other: Self) -> Self
Computes the four quadrant arctangent of self (y) and other (x).
x = 0,y = 0:0x >= 0:arctan(y/x)->[-pi/2, pi/2]y >= 0:arctan(y/x) + pi->(pi/2, pi]y < 0:arctan(y/x) - pi->(-pi, -pi/2)
use num::traits::Float; use std::f64; let pi = f64::consts::PI; // All angles from horizontal right (+x) // 45 deg counter-clockwise let x1 = 3.0; let y1 = -3.0; // 135 deg clockwise let x2 = -3.0; let y2 = 3.0; let abs_difference_1 = (y1.atan2(x1) - (-pi/4.0)).abs(); let abs_difference_2 = (y2.atan2(x2) - 3.0*pi/4.0).abs(); assert!(abs_difference_1 < 1e-10); assert!(abs_difference_2 < 1e-10);
fn sin_cos(self) -> (Self, Self)
Simultaneously computes the sine and cosine of the number, x. Returns
(sin(x), cos(x)).
use num::traits::Float; use std::f64; let x = f64::consts::PI/4.0; let f = x.sin_cos(); let abs_difference_0 = (f.0 - x.sin()).abs(); let abs_difference_1 = (f.1 - x.cos()).abs(); assert!(abs_difference_0 < 1e-10); assert!(abs_difference_0 < 1e-10);
fn exp_m1(self) -> Self
Returns e^(self) - 1 in a way that is accurate even if the
number is close to zero.
use num::traits::Float; let x = 7.0; // e^(ln(7)) - 1 let abs_difference = (x.ln().exp_m1() - 6.0).abs(); assert!(abs_difference < 1e-10);
fn ln_1p(self) -> Self
Returns ln(1+n) (natural logarithm) more accurately than if
the operations were performed separately.
use num::traits::Float; use std::f64; let x = f64::consts::E - 1.0; // ln(1 + (e - 1)) == ln(e) == 1 let abs_difference = (x.ln_1p() - 1.0).abs(); assert!(abs_difference < 1e-10);
fn sinh(self) -> Self
Hyperbolic sine function.
extern crate num; fn main() { use num::traits::Float; use std::f64; let e = f64::consts::E; let x = 1.0; let f = x.sinh(); // Solving sinh() at 1 gives `(e^2-1)/(2e)` let g = (e*e - 1.0)/(2.0*e); let abs_difference = (f - g).abs(); assert!(abs_difference < 1e-10); }use num::traits::Float; use std::f64; let e = f64::consts::E; let x = 1.0; let f = x.sinh(); // Solving sinh() at 1 gives `(e^2-1)/(2e)` let g = (e*e - 1.0)/(2.0*e); let abs_difference = (f - g).abs(); assert!(abs_difference < 1e-10);
fn cosh(self) -> Self
Hyperbolic cosine function.
extern crate num; fn main() { use num::traits::Float; use std::f64; let e = f64::consts::E; let x = 1.0; let f = x.cosh(); // Solving cosh() at 1 gives this result let g = (e*e + 1.0)/(2.0*e); let abs_difference = (f - g).abs(); // Same result assert!(abs_difference < 1.0e-10); }use num::traits::Float; use std::f64; let e = f64::consts::E; let x = 1.0; let f = x.cosh(); // Solving cosh() at 1 gives this result let g = (e*e + 1.0)/(2.0*e); let abs_difference = (f - g).abs(); // Same result assert!(abs_difference < 1.0e-10);
fn tanh(self) -> Self
Hyperbolic tangent function.
extern crate num; fn main() { use num::traits::Float; use std::f64; let e = f64::consts::E; let x = 1.0; let f = x.tanh(); // Solving tanh() at 1 gives `(1 - e^(-2))/(1 + e^(-2))` let g = (1.0 - e.powi(-2))/(1.0 + e.powi(-2)); let abs_difference = (f - g).abs(); assert!(abs_difference < 1.0e-10); }use num::traits::Float; use std::f64; let e = f64::consts::E; let x = 1.0; let f = x.tanh(); // Solving tanh() at 1 gives `(1 - e^(-2))/(1 + e^(-2))` let g = (1.0 - e.powi(-2))/(1.0 + e.powi(-2)); let abs_difference = (f - g).abs(); assert!(abs_difference < 1.0e-10);
fn asinh(self) -> Self
Inverse hyperbolic sine function.
extern crate num; fn main() { use num::traits::Float; let x = 1.0; let f = x.sinh().asinh(); let abs_difference = (f - x).abs(); assert!(abs_difference < 1.0e-10); }use num::traits::Float; let x = 1.0; let f = x.sinh().asinh(); let abs_difference = (f - x).abs(); assert!(abs_difference < 1.0e-10);
fn acosh(self) -> Self
Inverse hyperbolic cosine function.
extern crate num; fn main() { use num::traits::Float; let x = 1.0; let f = x.cosh().acosh(); let abs_difference = (f - x).abs(); assert!(abs_difference < 1.0e-10); }use num::traits::Float; let x = 1.0; let f = x.cosh().acosh(); let abs_difference = (f - x).abs(); assert!(abs_difference < 1.0e-10);
fn atanh(self) -> Self
Inverse hyperbolic tangent function.
extern crate num; fn main() { use num::traits::Float; use std::f64; let e = f64::consts::E; let f = e.tanh().atanh(); let abs_difference = (f - e).abs(); assert!(abs_difference < 1.0e-10); }use num::traits::Float; use std::f64; let e = f64::consts::E; let f = e.tanh().atanh(); let abs_difference = (f - e).abs(); assert!(abs_difference < 1.0e-10);
fn integer_decode(self) -> (u64, i16, i8)
Returns the mantissa, base 2 exponent, and sign as integers, respectively.
The original number can be recovered by sign * mantissa * 2 ^ exponent.
The floating point encoding is documented in the Reference.
use num::traits::Float; let num = 2.0f32; // (8388608, -22, 1) let (mantissa, exponent, sign) = Float::integer_decode(num); let sign_f = sign as f32; let mantissa_f = mantissa as f32; let exponent_f = num.powf(exponent as f32); // 1 * 8388608 * 2^(-22) == 2 let abs_difference = (sign_f * mantissa_f * exponent_f - num).abs(); assert!(abs_difference < 1e-10);