cosh(P)                                                 cosh(P)





NAME
       cosh, coshf, coshl - hyperbolic cosine functions

SYNOPSIS
       #include <math.h>

       double cosh(double x);
       float coshf(float x);
       long double coshl(long double x);


DESCRIPTION
       The  functionality  described  on this reference page is
       aligned with the ISO C standard.  Any  conflict  between
       the  requirements  described here and the ISO C standard
       is unintentional.  This volume  of  IEEE Std 1003.1-2001
       defers to the ISO C standard.

       These  functions  shall compute the hyperbolic cosine of
       their argument x.

       An application wishing to  check  for  error  situations
       should   set   errno   to   zero   and  call  feclearex-
       cept(FE_ALL_EXCEPT) before calling these functions.   On
       return,  if errno is non-zero or fetestexcept(FE_INVALID
       | FE_DIVBYZERO | FE_OVERFLOW  |  FE_UNDERFLOW)  is  non-
       zero, an error has occurred.

RETURN VALUE
       Upon successful completion, these functions shall return
       the hyperbolic cosine of x.

       If the correct value would cause overflow, a range error
       shall  occur  and  cosh(),  coshf(),  and  coshl() shall
       return the value of the macro HUGE_VAL,  HUGE_VALF,  and
       HUGE_VALL, respectively.

       If x is NaN, a NaN shall be returned.

       If x is +-0, the value 1.0 shall be returned.

       If x is +-Inf, +Inf shall be returned.

ERRORS
       These functions shall fail if:

       Range Error
              The result would cause an overflow.

       If    the   integer   expression   (math_errhandling   &
       MATH_ERRNO) is non-zero, then  errno  shall  be  set  to
       [ERANGE].  If the integer expression (math_errhandling &
       MATH_ERREXCEPT) is non-zero, then the overflow floating-
       point exception shall be raised.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       On    error,   the   expressions   (math_errhandling   &
       MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT)  are
       independent of each other, but at least one of them must
       be non-zero.

       For IEEE Std 754-1985 double, 710.5 < |x|  implies  that
       cosh( x) has overflowed.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       acosh()  ,  feclearexcept() , fetestexcept() , isnan() ,
       sinh()  ,  tanh()  ,  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001,  Section  4.18, Treatment of Error
       Conditions for Mathematical Functions, <math.h>

COPYRIGHT
       Portions of this text are reprinted  and  reproduced  in
       electronic  form  from  IEEE  Std  1003.1, 2003 Edition,
       Standard for Information Technology -- Portable  Operat-
       ing System Interface (POSIX), The Open Group Base Speci-
       fications Issue 6, Copyright (C) 2001-2003 by the Insti-
       tute  of  Electrical  and Electronics Engineers, Inc and
       The Open Group. In the event of any discrepancy  between
       this  version  and  the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard
       is  the  referee  document. The original Standard can be
       obtained        online        at        http://www.open-
       group.org/unix/online.html .



POSIX                         2003                      cosh(P)
