ftz, Qftz

Flushes denormal results to zero.

IDE Equivalent

Windows: Floating-Point > Flush Denormal Results to Zero
Linux: None

Architectures

IA-32, IntelŪ ItaniumŪ architecture

Syntax

Linux: -ftz
-no-ftz
Windows:  /Qftz
/Qftz-

Arguments

None

Default

OFF The compiler lets results gradually underflow.

Description

This option flushes denormal results to zero when the application is in the gradual underflow mode. It may improve performance if the denormal values are not critical to your application's behavior. On Itanium-based systems, optimization option O3 sets this option.

This option only has an effect when the main program is being compiled. It sets the FTZ mode for the process. The initial thread and any threads subsequently created by that process will operate in FTZ mode.

If this option produces undesirable results of the numerical behavior of your program, you can turn the FTZ mode off by using -no-ftz (Linux) or /Qftz- (Windows) in the command line while still benefiting from the O3 optimizations.

Optimization option O2 sets the -no-ftz (Linux) or /Qftz- (Windows) option.

Note

On IA-32 and IntelŪ EM64T systems, this option can degrade performance.

For more information, see Using the Floating-Point Exception Handling (/fpe) Compiler Option.

Alternate Options

None