feupdateenv(3M)

DESCRIPTION

The feupdateenv() function saves the currently raised floating-point exceptions in its automatic storage, installs the floating-point environment represented by the object pointed to by envp, and then raises the saved floating-point exceptions. Use feholdexcept() with feupdateenv() to hide spurious floating-point exceptions.

The argument envp must point to an object set by a call to fegetenv() or feholdexcept(), or equal the macro FE_DFL_ENV.

USAGE

To use this function, compile either with the default -Ae option or with the -Aa and -D_HPUX_SOURCE options. Make sure your program includes <fenv.h>.

For Itanium-based systems, specify +Ofenvaccess on the compiler command line or place the call to this function under the effect of an affirmative FENV_ACCESS pragma:

If the FENV_ACCESS pragma is placed outside of any top-level declarations in a file, the pragma will apply to all declarations in the compilation following the pragma until another FENV_ACCESS pragma is encountered or until the end of the file is reached.

If the FENV_ACCESS pragma is placed at the beginning of a block (compound statement), the pragma will apply until another FENV_ACCESS pragma is encountered or until the end of the block is reached.

For PA-RISC, you might need to use the +Onomoveflops compiler option in order to prevent optimizations that can undermine the specified behavior of this function.

Link in the math library by specifying -lm on the compiler or linker command line.

For more information, see the HP-UX Floating-Point Guide.

RETURN VALUE

ERRORS

No errors are defined.

EXAMPLES

Store the current floating-point environment in holdenv, hide spurious underflow exceptions, and continue on any floating-point exceptions that occur until the call to feupdateenv() is encountered.

SEE ALSO

fegetenv(3M), feholdexcept(3M), fesetenv(3M), fenv(5).

STANDARDS CONFORMANCE

feupdateenv() : ISO/IEC C99 (including Annex F, "IEC 60559 floating-point arithmetic")