From 9835e2ae736235810b4ea1c162ca5e65c547e770 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 18 May 2024 04:49:50 +0200 Subject: Merging upstream version 1.71.1+dfsg1. Signed-off-by: Daniel Baumann --- vendor/libm-0.1.4/src/math/k_sin.rs | 58 +++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 vendor/libm-0.1.4/src/math/k_sin.rs (limited to 'vendor/libm-0.1.4/src/math/k_sin.rs') diff --git a/vendor/libm-0.1.4/src/math/k_sin.rs b/vendor/libm-0.1.4/src/math/k_sin.rs new file mode 100644 index 000000000..5d2bd68aa --- /dev/null +++ b/vendor/libm-0.1.4/src/math/k_sin.rs @@ -0,0 +1,58 @@ +// origin: FreeBSD /usr/src/lib/msun/src/k_sin.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. +// ==================================================== + +const S1: f64 = -1.66666666666666324348e-01; /* 0xBFC55555, 0x55555549 */ +const S2: f64 = 8.33333333332248946124e-03; /* 0x3F811111, 0x1110F8A6 */ +const S3: f64 = -1.98412698298579493134e-04; /* 0xBF2A01A0, 0x19C161D5 */ +const S4: f64 = 2.75573137070700676789e-06; /* 0x3EC71DE3, 0x57B1FE7D */ +const S5: f64 = -2.50507602534068634195e-08; /* 0xBE5AE5E6, 0x8A2B9CEB */ +const S6: f64 = 1.58969099521155010221e-10; /* 0x3DE5D93A, 0x5ACFD57C */ + +// kernel sin function on ~[-pi/4, pi/4] (except on -0), pi/4 ~ 0.7854 +// Input x is assumed to be bounded by ~pi/4 in magnitude. +// Input y is the tail of x. +// Input iy indicates whether y is 0. (if iy=0, y assume to be 0). +// +// Algorithm +// 1. Since sin(-x) = -sin(x), we need only to consider positive x. +// 2. Callers must return sin(-0) = -0 without calling here since our +// odd polynomial is not evaluated in a way that preserves -0. +// Callers may do the optimization sin(x) ~ x for tiny x. +// 3. sin(x) is approximated by a polynomial of degree 13 on +// [0,pi/4] +// 3 13 +// sin(x) ~ x + S1*x + ... + S6*x +// where +// +// |sin(x) 2 4 6 8 10 12 | -58 +// |----- - (1+S1*x +S2*x +S3*x +S4*x +S5*x +S6*x )| <= 2 +// | x | +// +// 4. sin(x+y) = sin(x) + sin'(x')*y +// ~ sin(x) + (1-x*x/2)*y +// For better accuracy, let +// 3 2 2 2 2 +// r = x *(S2+x *(S3+x *(S4+x *(S5+x *S6)))) +// then 3 2 +// sin(x) = x + (S1*x + (x *(r-y/2)+y)) +#[inline] +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub(crate) fn k_sin(x: f64, y: f64, iy: i32) -> f64 { + let z = x * x; + let w = z * z; + let r = S2 + z * (S3 + z * S4) + z * w * (S5 + z * S6); + let v = z * x; + if iy == 0 { + x + v * (S1 + z * r) + } else { + x - ((z * (0.5 * y - v * r) - y) - v * S1) + } +} -- cgit v1.2.3