COSH(3P)                                            POSIX Programmer's Manual                                           COSH(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

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  inte-
       ger  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, Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                      COSH(3P)