s_tan.c File Reference

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

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Functions
double	tan (double x)

Function Documentation

double tan

(

double

x

)

Definition at line 45 of file s_tan.c.

References __ieee754_rem_pio2(), __kernel_tan(), and GET_HIGH_WORD.

Referenced by SDL_tan().

{
        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_tan(x,z,1);

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

    /* argument reduction needed */
        else {
            n = __ieee754_rem_pio2(x,y);
            return __kernel_tan(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
                                                        -1 -- n odd */
        }
}