sysdeps/ieee754/flt-32/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 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: s_tanf.c,v 1.4 1995/05/10 20:48:20 jtc Exp $";
  18 #endif
  19
  20 #include <errno.h>
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 #ifdef __STDC__
  25         float __tanf(float x)
  26 #else
  27         float __tanf(x)
  28         float x;
  29 #endif
  30 {
  31         float y[2],z=0.0;
  32         int32_t n, ix;
  33
  34         GET_FLOAT_WORD(ix,x);
  35
  36     /* |x| ~< pi/4 */
  37         ix &= 0x7fffffff;
  38         if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
  39
  40     /* tan(Inf or NaN) is NaN */
  41         else if (ix>=0x7f800000) {
  42           if (ix==0x7f800000)
  43             __set_errno (EDOM);
  44           return x-x;           /* NaN */
  45         }
  46
  47     /* argument reduction needed */
  48         else {
  49             n = __ieee754_rem_pio2f(x,y);
  50             return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
  51                                                               -1 -- n odd */
  52         }
  53 }
  54 weak_alias (__tanf, tanf)