diff options
Diffstat (limited to 'library/compiler-builtins/libm/src/math/lgammaf_r.rs')
| -rw-r--r-- | library/compiler-builtins/libm/src/math/lgammaf_r.rs | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm/src/math/lgammaf_r.rs b/library/compiler-builtins/libm/src/math/lgammaf_r.rs new file mode 100644 index 00000000000..10cecee541c --- /dev/null +++ b/library/compiler-builtins/libm/src/math/lgammaf_r.rs @@ -0,0 +1,256 @@ +/* origin: FreeBSD /usr/src/lib/msun/src/e_lgammaf_r.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::{floorf, k_cosf, k_sinf, logf}; + +const PI: f32 = 3.1415927410e+00; /* 0x40490fdb */ +const A0: f32 = 7.7215664089e-02; /* 0x3d9e233f */ +const A1: f32 = 3.2246702909e-01; /* 0x3ea51a66 */ +const A2: f32 = 6.7352302372e-02; /* 0x3d89f001 */ +const A3: f32 = 2.0580807701e-02; /* 0x3ca89915 */ +const A4: f32 = 7.3855509982e-03; /* 0x3bf2027e */ +const A5: f32 = 2.8905137442e-03; /* 0x3b3d6ec6 */ +const A6: f32 = 1.1927076848e-03; /* 0x3a9c54a1 */ +const A7: f32 = 5.1006977446e-04; /* 0x3a05b634 */ +const A8: f32 = 2.2086278477e-04; /* 0x39679767 */ +const A9: f32 = 1.0801156895e-04; /* 0x38e28445 */ +const A10: f32 = 2.5214456400e-05; /* 0x37d383a2 */ +const A11: f32 = 4.4864096708e-05; /* 0x383c2c75 */ +const TC: f32 = 1.4616321325e+00; /* 0x3fbb16c3 */ +const TF: f32 = -1.2148628384e-01; /* 0xbdf8cdcd */ +/* TT = -(tail of TF) */ +const TT: f32 = 6.6971006518e-09; /* 0x31e61c52 */ +const T0: f32 = 4.8383611441e-01; /* 0x3ef7b95e */ +const T1: f32 = -1.4758771658e-01; /* 0xbe17213c */ +const T2: f32 = 6.4624942839e-02; /* 0x3d845a15 */ +const T3: f32 = -3.2788541168e-02; /* 0xbd064d47 */ +const T4: f32 = 1.7970675603e-02; /* 0x3c93373d */ +const T5: f32 = -1.0314224288e-02; /* 0xbc28fcfe */ +const T6: f32 = 6.1005386524e-03; /* 0x3bc7e707 */ +const T7: f32 = -3.6845202558e-03; /* 0xbb7177fe */ +const T8: f32 = 2.2596477065e-03; /* 0x3b141699 */ +const T9: f32 = -1.4034647029e-03; /* 0xbab7f476 */ +const T10: f32 = 8.8108185446e-04; /* 0x3a66f867 */ +const T11: f32 = -5.3859531181e-04; /* 0xba0d3085 */ +const T12: f32 = 3.1563205994e-04; /* 0x39a57b6b */ +const T13: f32 = -3.1275415677e-04; /* 0xb9a3f927 */ +const T14: f32 = 3.3552918467e-04; /* 0x39afe9f7 */ +const U0: f32 = -7.7215664089e-02; /* 0xbd9e233f */ +const U1: f32 = 6.3282704353e-01; /* 0x3f2200f4 */ +const U2: f32 = 1.4549225569e+00; /* 0x3fba3ae7 */ +const U3: f32 = 9.7771751881e-01; /* 0x3f7a4bb2 */ +const U4: f32 = 2.2896373272e-01; /* 0x3e6a7578 */ +const U5: f32 = 1.3381091878e-02; /* 0x3c5b3c5e */ +const V1: f32 = 2.4559779167e+00; /* 0x401d2ebe */ +const V2: f32 = 2.1284897327e+00; /* 0x4008392d */ +const V3: f32 = 7.6928514242e-01; /* 0x3f44efdf */ +const V4: f32 = 1.0422264785e-01; /* 0x3dd572af */ +const V5: f32 = 3.2170924824e-03; /* 0x3b52d5db */ +const S0: f32 = -7.7215664089e-02; /* 0xbd9e233f */ +const S1: f32 = 2.1498242021e-01; /* 0x3e5c245a */ +const S2: f32 = 3.2577878237e-01; /* 0x3ea6cc7a */ +const S3: f32 = 1.4635047317e-01; /* 0x3e15dce6 */ +const S4: f32 = 2.6642270386e-02; /* 0x3cda40e4 */ +const S5: f32 = 1.8402845599e-03; /* 0x3af135b4 */ +const S6: f32 = 3.1947532989e-05; /* 0x3805ff67 */ +const R1: f32 = 1.3920053244e+00; /* 0x3fb22d3b */ +const R2: f32 = 7.2193557024e-01; /* 0x3f38d0c5 */ +const R3: f32 = 1.7193385959e-01; /* 0x3e300f6e */ +const R4: f32 = 1.8645919859e-02; /* 0x3c98bf54 */ +const R5: f32 = 7.7794247773e-04; /* 0x3a4beed6 */ +const R6: f32 = 7.3266842264e-06; /* 0x36f5d7bd */ +const W0: f32 = 4.1893854737e-01; /* 0x3ed67f1d */ +const W1: f32 = 8.3333335817e-02; /* 0x3daaaaab */ +const W2: f32 = -2.7777778450e-03; /* 0xbb360b61 */ +const W3: f32 = 7.9365057172e-04; /* 0x3a500cfd */ +const W4: f32 = -5.9518753551e-04; /* 0xba1c065c */ +const W5: f32 = 8.3633989561e-04; /* 0x3a5b3dd2 */ +const W6: f32 = -1.6309292987e-03; /* 0xbad5c4e8 */ + +/* sin(PI*x) assuming x > 2^-100, if sin(PI*x)==0 the sign is arbitrary */ +fn sin_pi(mut x: f32) -> f32 { + let mut y: f64; + let mut n: isize; + + /* spurious inexact if odd int */ + x = 2.0 * (x * 0.5 - floorf(x * 0.5)); /* x mod 2.0 */ + + n = (x * 4.0) as isize; + n = div!(n + 1, 2); + y = (x as f64) - (n as f64) * 0.5; + y *= 3.14159265358979323846; + match n { + 1 => k_cosf(y), + 2 => k_sinf(-y), + 3 => -k_cosf(y), + // 0 + _ => k_sinf(y), + } +} + +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub fn lgammaf_r(mut x: f32) -> (f32, i32) { + let u = x.to_bits(); + let mut t: f32; + let y: f32; + let mut z: f32; + let nadj: f32; + let p: f32; + let p1: f32; + let p2: f32; + let p3: f32; + let q: f32; + let mut r: f32; + let w: f32; + let ix: u32; + let i: i32; + let sign: bool; + let mut signgam: i32; + + /* purge off +-inf, NaN, +-0, tiny and negative arguments */ + signgam = 1; + sign = (u >> 31) != 0; + ix = u & 0x7fffffff; + if ix >= 0x7f800000 { + return (x * x, signgam); + } + if ix < 0x35000000 { + /* |x| < 2**-21, return -log(|x|) */ + if sign { + signgam = -1; + x = -x; + } + return (-logf(x), signgam); + } + if sign { + x = -x; + t = sin_pi(x); + if t == 0.0 { + /* -integer */ + return (1.0 / (x - x), signgam); + } + if t > 0.0 { + signgam = -1; + } else { + t = -t; + } + nadj = logf(PI / (t * x)); + } else { + nadj = 0.0; + } + + /* purge off 1 and 2 */ + if ix == 0x3f800000 || ix == 0x40000000 { + r = 0.0; + } + /* for x < 2.0 */ + else if ix < 0x40000000 { + if ix <= 0x3f666666 { + /* lgamma(x) = lgamma(x+1)-log(x) */ + r = -logf(x); + if ix >= 0x3f3b4a20 { + y = 1.0 - x; + i = 0; + } else if ix >= 0x3e6d3308 { + y = x - (TC - 1.0); + i = 1; + } else { + y = x; + i = 2; + } + } else { + r = 0.0; + if ix >= 0x3fdda618 { + /* [1.7316,2] */ + y = 2.0 - x; + i = 0; + } else if ix >= 0x3F9da620 { + /* [1.23,1.73] */ + y = x - TC; + i = 1; + } else { + y = x - 1.0; + i = 2; + } + } + match i { + 0 => { + z = y * y; + p1 = A0 + z * (A2 + z * (A4 + z * (A6 + z * (A8 + z * A10)))); + p2 = z * (A1 + z * (A3 + z * (A5 + z * (A7 + z * (A9 + z * A11))))); + p = y * p1 + p2; + r += p - 0.5 * y; + } + 1 => { + z = y * y; + w = z * y; + p1 = T0 + w * (T3 + w * (T6 + w * (T9 + w * T12))); /* parallel comp */ + p2 = T1 + w * (T4 + w * (T7 + w * (T10 + w * T13))); + p3 = T2 + w * (T5 + w * (T8 + w * (T11 + w * T14))); + p = z * p1 - (TT - w * (p2 + y * p3)); + r += TF + p; + } + 2 => { + p1 = y * (U0 + y * (U1 + y * (U2 + y * (U3 + y * (U4 + y * U5))))); + p2 = 1.0 + y * (V1 + y * (V2 + y * (V3 + y * (V4 + y * V5)))); + r += -0.5 * y + p1 / p2; + } + #[cfg(debug_assertions)] + _ => unreachable!(), + #[cfg(not(debug_assertions))] + _ => {} + } + } else if ix < 0x41000000 { + /* x < 8.0 */ + i = x as i32; + y = x - (i as f32); + p = y * (S0 + y * (S1 + y * (S2 + y * (S3 + y * (S4 + y * (S5 + y * S6)))))); + q = 1.0 + y * (R1 + y * (R2 + y * (R3 + y * (R4 + y * (R5 + y * R6))))); + r = 0.5 * y + p / q; + z = 1.0; /* lgamma(1+s) = log(s) + lgamma(s) */ + // TODO: In C, this was implemented using switch jumps with fallthrough. + // Does this implementation have performance problems? + if i >= 7 { + z *= y + 6.0; + } + if i >= 6 { + z *= y + 5.0; + } + if i >= 5 { + z *= y + 4.0; + } + if i >= 4 { + z *= y + 3.0; + } + if i >= 3 { + z *= y + 2.0; + r += logf(z); + } + } else if ix < 0x5c800000 { + /* 8.0 <= x < 2**58 */ + t = logf(x); + z = 1.0 / x; + y = z * z; + w = W0 + z * (W1 + y * (W2 + y * (W3 + y * (W4 + y * (W5 + y * W6))))); + r = (x - 0.5) * (t - 1.0) + w; + } else { + /* 2**58 <= x <= inf */ + r = x * (logf(x) - 1.0); + } + if sign { + r = nadj - r; + } + return (r, signgam); +} |