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fesetflushtozero(3m) [hpux man page]

fesetflushtozero(3M)													      fesetflushtozero(3M)

NAME
fesetflushtozero() - set floating-point underflow mode SYNOPSIS
DESCRIPTION
The function sets the current underflow mode. If the argument is 1, the underflow mode is set to flush-to-zero mode. If the argument is zero, the underflow mode is set to IEEE-754-compliant (gradual) underflow mode. For arguments other than 1 or zero, the effect is unde- fined. The default underflow mode is IEEE-754-compliant. Flush-to-zero mode, also known as fast underflow mode, is supported on most PA1.1 systems and on all PA2.0 and HP Integrity servers. In IEEE-754-compliant mode, cases that might underflow may be handled by trapping into the kernel, where the IEEE-mandated conversion of the result into a denormalized value or zero is accomplished by software emulation. On PA-RISC systems, flush-to-zero mode allows the substitution of a zero for denormal operands and operation results, without trapping into the kernel. On Integrity servers, flush-to-zero mode causes a zero to be substituted for denormal results (but not operands), without trapping into the kernel. Flush-to-zero mode may offer a significant performance improvement for some applications. USAGE
To use this function, compile either with the default option or with the and options. Make sure your program includes For Integrity servers, specify on the compiler command line or place the call to this function under the effect of an affirmative pragma: If the pragma is placed outside of any top-level declarations in a file, the pragma will apply to all declarations in the compilation fol- lowing the pragma until another pragma is encountered or until the end of the file is reached. If the pragma is placed at the beginning of a block (compound statement), the pragma will apply until another pragma is encountered or until the end of the block is reached. For PA-RISC, you might need to use the compiler option in order to prevent optimizations that can undermine the specified behavior of this function. Link in the math library by specifying on the compiler or linker command line. For more information, see the at the following site: RETURN VALUE
None. ERRORS
No errors are defined. EXAMPLES
Save the current underflow mode, set flush-to-zero mode, and restore the previous mode. AUTHOR
was developed by HP and is not required by any current standard. SEE ALSO
fegetflushtozero(3M), fenv(5). fesetflushtozero(3M)

Check Out this Related Man Page

feupdateenv(3M) 														   feupdateenv(3M)

NAME
feupdateenv() - update floating-point environment SYNOPSIS
HP Integrity Server Only PA-RISC Only DESCRIPTION
The function saves the currently raised floating-point exceptions in its automatic storage, installs the floating-point environment repre- sented by the object pointed to by envp, and then raises the saved floating-point exceptions. Use with to hide spurious floating-point exceptions. The argument envp must point to an object set by a call to or or equal the macro USAGE
To use this function, compile either with the default option or with the and options. Make sure your program includes For Integrity servers, specify on the compiler command line or place the call to this function under the effect of an affirmative pragma: If the pragma is placed outside of any top-level declarations in a file, the pragma will apply to all declarations in the compilation fol- lowing the pragma until another pragma is encountered or until the end of the file is reached. If the pragma is placed at the beginning of a block (compound statement), the pragma will apply until another pragma is encountered or until the end of the block is reached. For PA-RISC, you might need to use the compiler option in order to prevent optimizations that can undermine the specified behavior of this function. Link in the math library by specifying on the compiler or linker command line. For more information, see the at the following site: RETURN VALUE
Integrity Server Only This function always returns 0, indicating that all the actions were successfully carried out. PA-RISC Only None. ERRORS
No errors are defined. EXAMPLES
Store the current floating-point environment in hide spurious underflow exceptions, and continue on any floating-point exceptions that occur until the call to is encountered. SEE ALSO
fegetenv(3M), feholdexcept(3M), fesetenv(3M), fenv(5). STANDARDS CONFORMANCE
: ISO/IEC C99 (including Annex F, "IEC 60559 floating-point arithmetic") feupdateenv(3M)

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