- Specifies the semantics to be used. Possible values are:
- Disables optimizations that are not value-safe on floating-point data.
- Enables more aggressive optimizations on floating-point data.There is currently no difference betweenfast=1andfast=2.
- Enablesprecise, disables contractions, andenables pragmastdc fenv_access.
- The compiler uses more aggressive optimizations on floating-point calculations.
Tells the compiler to strictly adhere to value-safe optimizations when implementing floating-point calculations. It disables optimizations that can change the result of floating-point calculations
, which is required for strict ANSI conformance.
These semantics ensure the reproducibility of floating-point computations for serial code, including code vectorized or auto-parallelized by the compiler, but they may slow performance. They do not ensure value safety or run-to-run reproducibility of other parallel code.
Run-to-run reproducibility for floating-point reductions in OpenMP* code may be obtained for a fixed number of threads through the KMP_DETERMINISTIC_REDUCTION environment variable. For more information about this environment variable, see topic "Supported Environment Variables".
The compiler assumes the default floating-point environment; you are not allowed to modify it.
Tells the compiler to use more aggressive optimizations when implementing floating-point calculations. These optimizations increase speed,
but may affect the accuracy or reproducibility of floating-point computations.
There is currently no difference between fast=1 and fast=2.
Tells the compiler to strictly adhere to value-safe optimizations when implementing floating-point calculations and enables floating-point exception semantics. This is the strictest floating-point model.
The compiler does not assume the default floating-point environment; you are allowed to modify it.
- -fimf-accuracy-bits(Linux*) or/Qimf-accuracy-bits(Windows*)
- -fimf-max-error(Linux) or/Qimf-max-error(Windows)
- -fimf-precision(Linux) or/Qimf-precision(Windows)