toolchain/gcc/newlib/libm/math/w_cosh.c

   1
   2 /* @(#)w_cosh.c 5.1 93/09/24 */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, a Sun Microsystems, Inc. business.
   8  * Permission to use, copy, modify, and distribute this
   9  * software is freely granted, provided that this notice
  10  * is preserved.
  11  * ====================================================
  12  */
  13
  14 /*
  15
  16 FUNCTION
  17         <<cosh>>, <<coshf>>---hyperbolic cosine
  18
  19 ANSI_SYNOPSIS
  20         #include <math.h>
  21         double cosh(double <[x]>);
  22         float coshf(float <[x]>)
  23
  24 TRAD_SYNOPSIS
  25         #include <math.h>
  26         double cosh(<[x]>)
  27         double <[x]>;
  28
  29         float coshf(<[x]>)
  30         float <[x]>;
  31
  32 DESCRIPTION
  33
  34         <<cosh>> computes the hyperbolic cosine of the argument <[x]>.
  35         <<cosh(<[x]>)>> is defined as
  36         @ifnottex
  37         . (exp(x) + exp(-x))/2
  38         @end ifnottex
  39         @tex
  40         $${(e^x + e^{-x})} \over 2$$
  41         @end tex
  42
  43         Angles are specified in radians.
  44
  45         <<coshf>> is identical, save that it takes and returns <<float>>.
  46
  47 RETURNS
  48         The computed value is returned.  When the correct value would create
  49         an overflow,  <<cosh>> returns the value <<HUGE_VAL>> with the
  50         appropriate sign, and the global value <<errno>> is set to <<ERANGE>>.
  51
  52         You can modify error handling for these functions using the
  53         function <<matherr>>.
  54
  55 PORTABILITY
  56         <<cosh>> is ANSI.
  57         <<coshf>> is an extension.
  58
  59 QUICKREF
  60         cosh ansi pure
  61         coshf - pure
  62 */
  63
  64 /*
  65  * wrapper cosh(x)
  66  */
  67
  68 #include "fdlibm.h"
  69 #include <errno.h>
  70
  71 #ifndef _DOUBLE_IS_32BITS
  72
  73 #ifdef __STDC__
  74         double cosh(double x)           /* wrapper cosh */
  75 #else
  76         double cosh(x)                  /* wrapper cosh */
  77         double x;
  78 #endif
  79 {
  80 #ifdef _IEEE_LIBM
  81         return __ieee754_cosh(x);
  82 #else
  83         double z;
  84         struct exception exc;
  85         z = __ieee754_cosh(x);
  86         if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
  87         if(fabs(x)>7.10475860073943863426e+02) {
  88             /* cosh(finite) overflow */
  89 #ifndef HUGE_VAL
  90 #define HUGE_VAL inf
  91             double inf = 0.0;
  92
  93             SET_HIGH_WORD(inf,0x7ff00000);      /* set inf to infinite */
  94 #endif
  95             exc.type = OVERFLOW;
  96             exc.name = "cosh";
  97             exc.err = 0;
  98             exc.arg1 = exc.arg2 = x;
  99             if (_LIB_VERSION == _SVID_)
 100                exc.retval = HUGE;
 101             else
 102                exc.retval = HUGE_VAL;
 103             if (_LIB_VERSION == _POSIX_)
 104                errno = ERANGE;
 105             else if (!matherr(&exc)) {
 106                errno = ERANGE;
 107             }
 108             if (exc.err != 0)
 109                errno = exc.err;
 110             return exc.retval;
 111         } else
 112             return z;
 113 #endif
 114 }
 115
 116 #endif /* defined(_DOUBLE_IS_32BITS) */