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/* s_cosl.c -- long double version of s_sin.c.
* Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz.
*/
/*
* ====================================================
* 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.
* ====================================================
*/
/* sinl(x)
* Return sine function of x.
*
* kernel function:
* __kernel_sinl ... sine function on [-pi/4,pi/4]
* __kernel_cosl ... cose 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 "mathl.h"
#include "trigl.h"
#ifdef HAVE_SINL
#include "trigl.c"
#include "sincosl.c"
#endif
long double cosl(long double x)
{
long double y[2],z=0.0L;
int n;
/* |x| ~< pi/4 */
if(x >= -0.7853981633974483096156608458198757210492 &&
x <= 0.7853981633974483096156608458198757210492)
return kernel_cosl(x, z);
/* sinl(Inf or NaN) is NaN, sinl(0) is 0 */
else if ((x + x == x && x != 0.0) || x != x)
return x-x; /* NaN */
/* 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);
}
}
}
#if 0
int
main ()
{
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492));
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492 *29));
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492 *2));
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492 *30));
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492 *4));
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492 *32));
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492 *2/3));
printf ("%.16Lg\n", cosl(0.7853981633974483096156608458198757210492 *4/3));
}
#endif