xref: /bionic/libm/src/k_cosf.c

/* k_cosf.c -- float version of k_cos.c
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 * Debugged and optimized by Bruce D. Evans.
 */

/*
 * ====================================================
 * 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.
 * ====================================================
 */

#ifndef INLINE_KERNEL_COSDF
#ifndef lint
static char rcsid[] = "$FreeBSD: src/lib/msun/src/k_cosf.c,v 1.15 2005/11/30 11:51:17 bde Exp $";
#endif
#endif

#include "math.h"
#include "math_private.h"

/* |cos(x) - c(x)| < 2**-34.1 (~[-5.37e-11, 5.295e-11]). */
static const double
one =  1.0,
C0  = -0x1ffffffd0c5e81.0p-54,	/* -0.499999997251031003120 */
C1  =  0x155553e1053a42.0p-57,	/*  0.0416666233237390631894 */
C2  = -0x16c087e80f1e27.0p-62,	/* -0.00138867637746099294692 */
C3  =  0x199342e0ee5069.0p-68;	/*  0.0000243904487962774090654 */

#ifdef INLINE_KERNEL_COSDF
extern inline
#endif
float
__kernel_cosdf(double x)
{
	double r, w, z;

	/* Try to optimize for parallel evaluation as in k_tanf.c. */
	z = x*x;
	w = z*z;
	r = C2+z*C3;
	return ((one+z*C0) + w*C1) + (w*z)*r;
}