mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-19 11:30:06 +00:00
89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
/* s_cosl.c -- long double version of s_cos.c.
|
|
* Conversion to long double by Ulrich Drepper,
|
|
* Cygnus Support, drepper@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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
static char rcsid[] = "$NetBSD: $";
|
|
#endif
|
|
|
|
/* cosl(x)
|
|
* Return cosine function of x.
|
|
*
|
|
* kernel function:
|
|
* __kernel_sinl ... sine function on [-pi/4,pi/4]
|
|
* __kernel_cosl ... cosine function on [-pi/4,pi/4]
|
|
* __ieee754_rem_pio2l ... 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
|
|
*/
|
|
|
|
#include "math.h"
|
|
#include "math_private.h"
|
|
|
|
#ifdef __STDC__
|
|
long double __cosl(long double x)
|
|
#else
|
|
long double __cosl(x)
|
|
long double x;
|
|
#endif
|
|
{
|
|
long double y[2],z=0.0;
|
|
int32_t n, se, i0, i1;
|
|
|
|
/* High word of x. */
|
|
GET_LDOUBLE_WORDS(se,i0,i1,x);
|
|
|
|
/* |x| ~< pi/4 */
|
|
se &= 0x7fff;
|
|
if(se < 0x3ffe || (se == 0x3ffe && i0 <= 0xc90fdaa2))
|
|
return __kernel_cosl(x,z);
|
|
|
|
/* cos(Inf or NaN) is NaN */
|
|
else if (se==0x7fff) return x-x;
|
|
|
|
/* argument reduction needed */
|
|
else {
|
|
n = __ieee754_rem_pio2l(x,y);
|
|
switch(n&3) {
|
|
case 0: return __kernel_cosl(y[0],y[1]);
|
|
case 1: return -__kernel_sinl(y[0],y[1],1);
|
|
case 2: return -__kernel_cosl(y[0],y[1]);
|
|
default:
|
|
return __kernel_sinl(y[0],y[1],1);
|
|
}
|
|
}
|
|
}
|
|
weak_alias (__cosl, cosl)
|