-fnonstd

Initialize floating-point hardware to non-standard preferences.

SPARC: 77/90 x86:77

This option is a synonym for the combination of the following option flags:

• SPARC: -fns  -ftrap=common

• x86: -ftrap=common

Specifying -fnonstd is approximately equivalent to the following two calls at the beginning of a Fortran main program.

i=ieee_handler("set", "common", SIGFPE_ABORT)
call nonstandard_arithmetic() 

The nonstandard_arithmetic() routine replaces the obsolete abrupt_underflow() routine of earlier releases.

To be effective, the main program must be compiled with this option.

Using this option initializes the floating-point hardware to:

• Abort (trap) on floating-point exceptions.

• SPARC: Flush underflow results to zero if it will improve speed, rather than produce a subnormal number as the IEEE standard requires.

See -fns for more information about gradual underflow and subnormal numbers.

The -fnonstd option allows hardware traps to be enabled for floating-point overflow, division by zero, and invalid operation exceptions. These are converted into SIGFPE signals, and if the program has no SIGFPE handler, it terminates with a dump of memory.

For more information, see the ieee_handler(3m) and ieee_functions(3m) man pages, the Numerical Computation Guide, and the Fortran Programming Guide.