The options described in this section all provide optimizations with varying degrees of precision in floating-point (FP) arithmetic for IA-32 and Itanium(TM) compiler. See the FP arithmetic precision options summary.
The -mp, -mp1, and -doubletemps options are used by both architectures. Use the -doubletemps option to ensure that all intermediate results of floating-point expressions are maintained in at least double precision, both for IA-32 and Itanium-based applications.
The FP options provide optimizations with varying degrees of precision in floating-point arithmetic. The option that disables these optimizations is -O0.
Use -mp to limit floating-point optimizations and maintain declared precision. For example, the Intel® Fortran Compiler can change floating-point division computations into multiplication by the reciprocal of the denominator. This change can alter the results of floating point division computations slightly. The -mp switch may slightly reduce execution speed. See Maintaining and /Restricting FP Arithmetic Precision for more detail.
Use the -mp1 option to restrict floating-point precision to be closer to declared precision with less impact to performance than with the -mp option. The option will ensure the out-of-range check of operands of transcendental functions and improve accuracy of floating-point compares.