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

       feupdateenv — update floating-point environment

SYNOPSIS

       #include <fenv.h>

       int feupdateenv(const fenv_t *envp);

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.1‐2017 defers to the ISO C standard.

       The  feupdateenv()  function  shall  attempt  to  save the currently raised floating-point
       exceptions in its automatic storage, attempt to  install  the  floating-point  environment
       represented  by  the  object  pointed  to  by  envp,  and  then attempt to raise the saved
       floating-point exceptions. The argument envp shall point to an object set  by  a  call  to
       feholdexcept() or fegetenv(), or equal a floating-point environment macro.

RETURN VALUE

       The  feupdateenv()  function  shall  return  a  zero value if and only if all the required
       actions were successfully carried out.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       The following  example  shows  sample  code  to  hide  spurious  underflow  floating-point
       exceptions:

           #include <fenv.h>
           double f(double x)
           {
               #pragma STDC FENV_ACCESS ON
               double result;
               fenv_t save_env;
               feholdexcept(&save_env);
               // compute result
               if (/* test spurious underflow */)
               feclearexcept(FE_UNDERFLOW);
               feupdateenv(&save_env);
               return result;
           }

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fegetenv(), feholdexcept()

       The Base Definitions volume of POSIX.1‐2017, <fenv.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       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 .