PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult 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

       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 POSIX.1‐2008 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
       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 POSIX.1‐2008, Section 4.19, 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, 2013 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX),  The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .