vendor/compiler_builtins/libm/src/math/k_cosf.rs

   1 /* origin: FreeBSD /usr/src/lib/msun/src/k_cosf.c */
   2 /*
   3  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   4  * Debugged and optimized by Bruce D. Evans.
   5  */
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 /* |cos(x) - c(x)| < 2**-34.1 (~[-5.37e-11, 5.295e-11]). */
  18 const C0: f64 = -0.499999997251031003120; /* -0x1ffffffd0c5e81.0p-54 */
  19 const C1: f64 = 0.0416666233237390631894; /*  0x155553e1053a42.0p-57 */
  20 const C2: f64 = -0.00138867637746099294692; /* -0x16c087e80f1e27.0p-62 */
  21 const C3: f64 = 0.0000243904487962774090654; /*  0x199342e0ee5069.0p-68 */
  22
  23 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
  24 pub(crate) fn k_cosf(x: f64) -> f32 {
  25     let z = x * x;
  26     let w = z * z;
  27     let r = C2 + z * C3;
  28     (((1.0 + z * C0) + w * C1) + (w * z) * r) as f32
  29 }