3 
Do not use this option for programs that depend on IEEE standard exception handling; you can get different numerical results, premature program termination, or unexpected SIGFPE signals.
Note – The criteria for the -fast option vary with the compilers from SunSoft: C, C++, FORTRAN 77, Fortran 90, and Pascal. See the appropriate documentation for the specifics.
-fnonstd
The -fnonstdoption causes nonstandard initialization of floating-point arithmetic hardware. By default, IEEE 754 floating-point arithmetic is nonstop, and underflows are gradual. (See the Numerical Computation Guide for details.) The –fnonstdoption causes hardware traps to be enabled for floating-point overflow, division by zero, and invalid operation exceptions. These hardware traps are converted into SIGFPE signals, and if the program has no SIGFPE handler, it terminates with a memory dump.
-fnonstdalso causes the math library to be linked in by passing -lmto the linker.
(Solaris 2.x only) This option is a synonym for -fns-ftrap=common.
–fns
(Solaris 2.x only) The -fnsoption turns on the SPARC non-standard floating- point mode.
The default is the SPARC standard floating-point mode.
If you compile one routine with -fns, then compile all routines of the program with the –fnsoption; otherwise, unexpected results may occur.
–fround=r
(Solaris 2.x only) The -fround=roption sets the IEEE 754 rounding mode that is established during program initialization.
r must be one of: nearest, tozero, negative, positive.