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

#include <config.h>

/* Specification.  */
#include <math.h>

/* 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 "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;

    /* cosl(NaN) is NaN */
        if (isnanl (x))
          return x;

    /* |x| ~< pi/4 */
        if(x >= -0.7853981633974483096156608458198757210492 &&
           x <= 0.7853981633974483096156608458198757210492)
          return kernel_cosl(x, z);

    /* cosl(Inf) is NaN, cosl(0) is 1 */
        else if (x + x == x && x != 0.0)
          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 (void)
{
  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