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 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, Copyright (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.opengroup.org/unix/online.html .