s_cos.c File Reference

#include "math_libm.h"
#include "math_private.h"

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Functions
double	cos (double x)

Function Documentation

double cos

(

double

x

)

Definition at line 46 of file s_cos.c.

References __ieee754_rem_pio2(), __kernel_cos(), __kernel_sin(), and GET_HIGH_WORD.

Referenced by SDL_cos().

{
        double y[2],z=0.0;
        int32_t n, ix;

    /* High word of x. */
        GET_HIGH_WORD(ix,x);

    /* |x| ~< pi/4 */
        ix &= 0x7fffffff;
        if(ix <= 0x3fe921fb) return __kernel_cos(x,z);

    /* cos(Inf or NaN) is NaN */
        else if (ix>=0x7ff00000) return x-x;

    /* argument reduction needed */
        else {
            n = __ieee754_rem_pio2(x,y);
            switch(n&3) {
                case 0: return  __kernel_cos(y[0],y[1]);
                case 1: return -__kernel_sin(y[0],y[1],1);
                case 2: return -__kernel_cos(y[0],y[1]);
                default:
                        return  __kernel_sin(y[0],y[1],1);
            }
        }
}