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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
commit698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch)
tree173a775858bd501c378080a10dca74132f05bc50 /vendor/compiler_builtins/libm/src/math/sin.rs
parentInitial commit. (diff)
downloadrustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz
rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/compiler_builtins/libm/src/math/sin.rs')
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diff --git a/vendor/compiler_builtins/libm/src/math/sin.rs b/vendor/compiler_builtins/libm/src/math/sin.rs
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+// origin: FreeBSD /usr/src/lib/msun/src/s_sin.c */
+//
+// ====================================================
+// 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::{k_cos, k_sin, rem_pio2};
+
+// sin(x)
+// Return sine function of x.
+//
+// kernel function:
+// k_sin ... sine function on [-pi/4,pi/4]
+// k_cos ... cose function on [-pi/4,pi/4]
+// rem_pio2 ... argument reduction routine
+//
+// Method.
+// Let S,C and T denote the sin, cos and tan respectively on
+// [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
+// in [-pi/4 , +pi/4], and let n = k mod 4.
+// We have
+//
+// n sin(x) cos(x) tan(x)
+// ----------------------------------------------------------
+// 0 S C T
+// 1 C -S -1/T
+// 2 -S -C T
+// 3 -C S -1/T
+// ----------------------------------------------------------
+//
+// Special cases:
+// Let trig be any of sin, cos, or tan.
+// trig(+-INF) is NaN, with signals;
+// trig(NaN) is that NaN;
+//
+// Accuracy:
+// TRIG(x) returns trig(x) nearly rounded
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn sin(x: f64) -> f64 {
+ let x1p120 = f64::from_bits(0x4770000000000000); // 0x1p120f === 2 ^ 120
+
+ /* High word of x. */
+ let ix = (f64::to_bits(x) >> 32) as u32 & 0x7fffffff;
+
+ /* |x| ~< pi/4 */
+ if ix <= 0x3fe921fb {
+ if ix < 0x3e500000 {
+ /* |x| < 2**-26 */
+ /* raise inexact if x != 0 and underflow if subnormal*/
+ if ix < 0x00100000 {
+ force_eval!(x / x1p120);
+ } else {
+ force_eval!(x + x1p120);
+ }
+ return x;
+ }
+ return k_sin(x, 0.0, 0);
+ }
+
+ /* sin(Inf or NaN) is NaN */
+ if ix >= 0x7ff00000 {
+ return x - x;
+ }
+
+ /* argument reduction needed */
+ let (n, y0, y1) = rem_pio2(x);
+ match n & 3 {
+ 0 => k_sin(y0, y1, 1),
+ 1 => k_cos(y0, y1),
+ 2 => -k_sin(y0, y1, 1),
+ _ => -k_cos(y0, y1),
+ }
+}
+
+#[test]
+fn test_near_pi() {
+ let x = f64::from_bits(0x400921fb000FD5DD); // 3.141592026217707
+ let sx = f64::from_bits(0x3ea50d15ced1a4a2); // 6.273720864039205e-7
+ let result = sin(x);
+ #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))]
+ let result = force_eval!(result);
+ assert_eq!(result, sx);
+}