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Diffstat (limited to '')
-rw-r--r-- | vendor/compiler_builtins/libm/src/math/atanf.rs | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/atanf.rs b/vendor/compiler_builtins/libm/src/math/atanf.rs new file mode 100644 index 000000000..d042b3bc0 --- /dev/null +++ b/vendor/compiler_builtins/libm/src/math/atanf.rs @@ -0,0 +1,112 @@ +/* origin: FreeBSD /usr/src/lib/msun/src/s_atanf.c */ +/* + * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. + */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +use super::fabsf; + +const ATAN_HI: [f32; 4] = [ + 4.6364760399e-01, /* atan(0.5)hi 0x3eed6338 */ + 7.8539812565e-01, /* atan(1.0)hi 0x3f490fda */ + 9.8279368877e-01, /* atan(1.5)hi 0x3f7b985e */ + 1.5707962513e+00, /* atan(inf)hi 0x3fc90fda */ +]; + +const ATAN_LO: [f32; 4] = [ + 5.0121582440e-09, /* atan(0.5)lo 0x31ac3769 */ + 3.7748947079e-08, /* atan(1.0)lo 0x33222168 */ + 3.4473217170e-08, /* atan(1.5)lo 0x33140fb4 */ + 7.5497894159e-08, /* atan(inf)lo 0x33a22168 */ +]; + +const A_T: [f32; 5] = [ + 3.3333328366e-01, + -1.9999158382e-01, + 1.4253635705e-01, + -1.0648017377e-01, + 6.1687607318e-02, +]; + +/// Arctangent (f32) +/// +/// Computes the inverse tangent (arc tangent) of the input value. +/// Returns a value in radians, in the range of -pi/2 to pi/2. +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub fn atanf(mut x: f32) -> f32 { + let x1p_120 = f32::from_bits(0x03800000); // 0x1p-120 === 2 ^ (-120) + + let z: f32; + + let mut ix = x.to_bits(); + let sign = (ix >> 31) != 0; + ix &= 0x7fffffff; + + if ix >= 0x4c800000 { + /* if |x| >= 2**26 */ + if x.is_nan() { + return x; + } + z = i!(ATAN_HI, 3) + x1p_120; + return if sign { -z } else { z }; + } + let id = if ix < 0x3ee00000 { + /* |x| < 0.4375 */ + if ix < 0x39800000 { + /* |x| < 2**-12 */ + if ix < 0x00800000 { + /* raise underflow for subnormal x */ + force_eval!(x * x); + } + return x; + } + -1 + } else { + x = fabsf(x); + if ix < 0x3f980000 { + /* |x| < 1.1875 */ + if ix < 0x3f300000 { + /* 7/16 <= |x| < 11/16 */ + x = (2. * x - 1.) / (2. + x); + 0 + } else { + /* 11/16 <= |x| < 19/16 */ + x = (x - 1.) / (x + 1.); + 1 + } + } else if ix < 0x401c0000 { + /* |x| < 2.4375 */ + x = (x - 1.5) / (1. + 1.5 * x); + 2 + } else { + /* 2.4375 <= |x| < 2**26 */ + x = -1. / x; + 3 + } + }; + /* end of argument reduction */ + z = x * x; + let w = z * z; + /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */ + let s1 = z * (i!(A_T, 0) + w * (i!(A_T, 2) + w * i!(A_T, 4))); + let s2 = w * (i!(A_T, 1) + w * i!(A_T, 3)); + if id < 0 { + return x - x * (s1 + s2); + } + let id = id as usize; + let z = i!(ATAN_HI, id) - ((x * (s1 + s2) - i!(ATAN_LO, id)) - x); + if sign { + -z + } else { + z + } +} |