toolchain/gcc/newlib/libm/mathfp/s_cosh.c

   1
   2 /* @(#)z_cosh.c 1.0 98/08/13 */
   3
   4 /*
   5
   6 FUNCTION
   7         <<cosh>>, <<coshf>>---hyperbolic cosine
   8
   9 ANSI_SYNOPSIS
  10         #include <math.h>
  11         double cosh(double <[x]>);
  12         float coshf(float <[x]>)
  13
  14 TRAD_SYNOPSIS
  15         #include <math.h>
  16         double cosh(<[x]>)
  17         double <[x]>;
  18
  19         float coshf(<[x]>)
  20         float <[x]>;
  21
  22 DESCRIPTION
  23
  24         <<cosh>> computes the hyperbolic cosine of the argument <[x]>.
  25         <<cosh(<[x]>)>> is defined as
  26         @ifnottex
  27         . (exp(x) + exp(-x))/2
  28         @end ifnottex
  29         @tex
  30         $${(e^x + e^{-x})} \over 2$$
  31         @end tex
  32
  33         Angles are specified in radians.
  34
  35         <<coshf>> is identical, save that it takes and returns <<float>>.
  36
  37 RETURNS
  38         The computed value is returned.  When the correct value would create
  39         an overflow,  <<cosh>> returns the value <<HUGE_VAL>> with the
  40         appropriate sign, and the global value <<errno>> is set to <<ERANGE>>.
  41
  42         You can modify error handling for these functions using the
  43         function <<matherr>>.
  44
  45 PORTABILITY
  46         <<cosh>> is ANSI.
  47         <<coshf>> is an extension.
  48
  49 QUICKREF
  50         cosh ansi pure
  51         coshf - pure
  52 */
  53
  54 /******************************************************************
  55  * Hyperbolic Cosine
  56  *
  57  * Input:
  58  *   x - floating point value
  59  *
  60  * Output:
  61  *   hyperbolic cosine of x
  62  *
  63  * Description:
  64  *   This routine returns the hyperbolic cosine of x.
  65  *
  66  *****************************************************************/
  67
  68 #include "fdlibm.h"
  69 #include "zmath.h"
  70
  71 #ifndef _DOUBLE_IS_32BITS
  72
  73 double
  74 _DEFUN (cosh, (double),
  75         double x)
  76 {
  77   return (sineh (x, 1));
  78 }
  79
  80 #endif /* _DOUBLE_IS_32BITS */