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

       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
       feclearexcept(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  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute 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.opengroup.org/unix/online.html .