How to set FTZ and DAZ flag for ifc 7.1 ?

[dfumento5]

The ifc 7.1 manuals are no longer available. I can see how in ifort
version 8 how to set FTZ (-ftz) and the DAZ flag is set automatically for P3 and above.

There is no -ftz flag for ifc 7.1. Also how do you set the DAZ flag in ifc 7.1?

Thanks,
David

[TimP]

The primary alternative to the command line option, which would set mxcsr in main(), is to use the setcsr() intrinsics from . A call to a simple gcc function would do. IIRC, there was no change in the way DAZ was handled between 7.1 and 8.0.

[dfumento5]

Could you tell me the exact 'C' subroutine for setting the FTZ bit?

Thanks,
David

[TimP]

e.g. Fortran code:

call setftz

...

C code:

#include

void setftz_(){

_MM_SET_FLUSH_ZERO_MODE (_MM_FLUSH_ZERO_ON);

}

While not standard C syntax, it is supported by current gcc, icc, and MSVC compilers, as well as (supposedly), by PGI C and Fortran compilers.

[dfumento]

Thanks!