gonzui

    1: /* s_tanf.c -- float version of s_tan.c.
    2:  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
    3:  */
    4: 
    5: /*
    6:  * ====================================================
    7:  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
    8:  *
    9:  * Developed at SunPro, a Sun Microsystems, Inc. business.
   10:  * Permission to use, copy, modify, and distribute this
   11:  * software is freely granted, provided that this notice 
   12:  * is preserved.
   13:  * ====================================================
   14:  */
   15: 
   16: #include "math.h"
   17: #include "math_private.h"
   18: 
   19: float
   20: tanf(float x)
   21: {
   22:         float y[2],z=0.0;
   23:         int32_t n, ix;
   24: 
   25:         GET_FLOAT_WORD(ix,x);
   26: 
   27:     /* |x| ~< pi/4 */
   28:         ix &= 0x7fffffff;
   29:         if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
   30: 
   31:     /* tan(Inf or NaN) is NaN */
   32:         else if (ix>=0x7f800000) return x-x;           /* NaN */
   33: 
   34:     /* argument reduction needed */
   35:         else {
   36:             n = __ieee754_rem_pio2f(x,y);
   37:             return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
   38:                                                               -1 -- n odd */
   39:         }
   40: }