lib/libm/src/s_tanf.c

   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 <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: s_tanf.c,v 1.7 2002/05/26 22:01:58 wiz Exp $");
  19 #endif
  20
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 float
  25 tanf(float x)
  26 {
  27         float y[2],z=0.0;
  28         int32_t n, ix;
  29
  30         GET_FLOAT_WORD(ix,x);
  31
  32     /* |x| ~< pi/4 */
  33         ix &= 0x7fffffff;
  34         if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
  35
  36     /* tan(Inf or NaN) is NaN */
  37         else if (ix>=0x7f800000) return x-x;            /* NaN */
  38
  39     /* argument reduction needed */
  40         else {
  41             n = __ieee754_rem_pio2f(x,y);
  42             return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
  43                                                               -1 -- n odd */
  44         }
  45 }