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 (con-
       sult 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 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 IEEE Std 1003.1-2001, <fenv.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                                               FEUPDATEENV(3P)