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Diffstat (limited to 'vendor/libm-0.1.4/src/math/acos.rs')
| -rw-r--r-- | vendor/libm-0.1.4/src/math/acos.rs | 114 |
1 files changed, 0 insertions, 114 deletions
diff --git a/vendor/libm-0.1.4/src/math/acos.rs b/vendor/libm-0.1.4/src/math/acos.rs deleted file mode 100644 index d5e1f6865..000000000 --- a/vendor/libm-0.1.4/src/math/acos.rs +++ /dev/null @@ -1,114 +0,0 @@ -/* origin: FreeBSD /usr/src/lib/msun/src/e_acos.c */ -/* - * ==================================================== - * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. - * - * Developed at SunSoft, a Sun Microsystems, Inc. business. - * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice - * is preserved. - * ==================================================== - */ -/* acos(x) - * Method : - * acos(x) = pi/2 - asin(x) - * acos(-x) = pi/2 + asin(x) - * For |x|<=0.5 - * acos(x) = pi/2 - (x + x*x^2*R(x^2)) (see asin.c) - * For x>0.5 - * acos(x) = pi/2 - (pi/2 - 2asin(sqrt((1-x)/2))) - * = 2asin(sqrt((1-x)/2)) - * = 2s + 2s*z*R(z) ...z=(1-x)/2, s=sqrt(z) - * = 2f + (2c + 2s*z*R(z)) - * where f=hi part of s, and c = (z-f*f)/(s+f) is the correction term - * for f so that f+c ~ sqrt(z). - * For x<-0.5 - * acos(x) = pi - 2asin(sqrt((1-|x|)/2)) - * = pi - 0.5*(s+s*z*R(z)), where z=(1-|x|)/2,s=sqrt(z) - * - * Special cases: - * if x is NaN, return x itself; - * if |x|>1, return NaN with invalid signal. - * - * Function needed: sqrt - */ - -use super::sqrt; - -const PIO2_HI: f64 = 1.57079632679489655800e+00; /* 0x3FF921FB, 0x54442D18 */ -const PIO2_LO: f64 = 6.12323399573676603587e-17; /* 0x3C91A626, 0x33145C07 */ -const PS0: f64 = 1.66666666666666657415e-01; /* 0x3FC55555, 0x55555555 */ -const PS1: f64 = -3.25565818622400915405e-01; /* 0xBFD4D612, 0x03EB6F7D */ -const PS2: f64 = 2.01212532134862925881e-01; /* 0x3FC9C155, 0x0E884455 */ -const PS3: f64 = -4.00555345006794114027e-02; /* 0xBFA48228, 0xB5688F3B */ -const PS4: f64 = 7.91534994289814532176e-04; /* 0x3F49EFE0, 0x7501B288 */ -const PS5: f64 = 3.47933107596021167570e-05; /* 0x3F023DE1, 0x0DFDF709 */ -const QS1: f64 = -2.40339491173441421878e+00; /* 0xC0033A27, 0x1C8A2D4B */ -const QS2: f64 = 2.02094576023350569471e+00; /* 0x40002AE5, 0x9C598AC8 */ -const QS3: f64 = -6.88283971605453293030e-01; /* 0xBFE6066C, 0x1B8D0159 */ -const QS4: f64 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */ - -#[inline] -fn r(z: f64) -> f64 { - let p: f64 = z * (PS0 + z * (PS1 + z * (PS2 + z * (PS3 + z * (PS4 + z * PS5))))); - let q: f64 = 1.0 + z * (QS1 + z * (QS2 + z * (QS3 + z * QS4))); - p / q -} - -/// Arccosine (f64) -/// -/// Computes the inverse cosine (arc cosine) of the input value. -/// Arguments must be in the range -1 to 1. -/// Returns values in radians, in the range of 0 to pi. -#[inline] -#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] -pub fn acos(x: f64) -> f64 { - let x1p_120f = f64::from_bits(0x3870000000000000); // 0x1p-120 === 2 ^ -120 - let z: f64; - let w: f64; - let s: f64; - let c: f64; - let df: f64; - let hx: u32; - let ix: u32; - - hx = (x.to_bits() >> 32) as u32; - ix = hx & 0x7fffffff; - /* |x| >= 1 or nan */ - if ix >= 0x3ff00000 { - let lx: u32 = x.to_bits() as u32; - - if ((ix - 0x3ff00000) | lx) == 0 { - /* acos(1)=0, acos(-1)=pi */ - if (hx >> 31) != 0 { - return 2. * PIO2_HI + x1p_120f; - } - return 0.; - } - return 0. / (x - x); - } - /* |x| < 0.5 */ - if ix < 0x3fe00000 { - if ix <= 0x3c600000 { - /* |x| < 2**-57 */ - return PIO2_HI + x1p_120f; - } - return PIO2_HI - (x - (PIO2_LO - x * r(x * x))); - } - /* x < -0.5 */ - if (hx >> 31) != 0 { - z = (1.0 + x) * 0.5; - s = sqrt(z); - w = r(z) * s - PIO2_LO; - return 2. * (PIO2_HI - (s + w)); - } - /* x > 0.5 */ - z = (1.0 - x) * 0.5; - s = sqrt(z); - // Set the low 4 bytes to zero - df = f64::from_bits(s.to_bits() & 0xff_ff_ff_ff_00_00_00_00); - - c = (z - df * df) / (s + df); - w = r(z) * s + c; - 2. * (df + w) -} |