huschi.net

FEUPDATEENV(3P)            POSIX Programmer's Manual           FEUPDATEENV(3P)
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.1-2008
       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 feholdex-
       cept() 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.1-2008, <fenv.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 Electri-
       cal 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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                      FEUPDATEENV(3P)