# fimf-arch-consistency, Qimf-arch-consistency

Ensures that the math library functions produce consistent results across different microarchitectural implementations of the same architecture.

## Syntax

Linux: | -fimf-arch-consistency=value[:funclist]

macOS: | -fimf-arch-consistency=value[:funclist]

Windows: | /Qimf-arch-consistency:value[:funclist]

Optional argument funclist is not supported for ifx.

## Arguments

value | Is one of the logical values "true" or "false".
funclist | Is an optional list of one or more math library functions to which the attribute should be applied. Do not specify the standard Fortran name of the math function; you must specify the actual math library name. If you specify more than one function, they must be separated with commas. Precision-specific variants like sin and sinf are considered different functions, so you would need to use -fimf-arch-consistency=true:sin,sinf (or /Qimf-arch-consistency:true:sin,sinf) to specify consistent results for both the single-precision and double-precision sine functions. You also can specify the symbol /f to denote single-precision divides, symbol / to denote double-precision divides, symbol /l to denote extended-precision divides, and symbol /q to denote quad-precision divides. For example you can specify -fimf-arch-consistency=true:/ or /Qimf-arch-consistency:true:/.

## Default

false | Implementations of some math library functions may produce slightly different results on implementations of the same architecture.

## Description

This option ensures that the math library functions produce consistent results across different microarchitectural implementations of the same architecture (for example, across different microarchitectural implementations of IA-32 architecture). Consistency is only guaranteed for a single binary. Consistency is not guaranteed across different architectures. For example, consistency is not guaranteed across IA-32 architecture and Intel® 64 architecture.

If you need to define the accuracy for a math function of a certain precision, specify the function name of the precision that you need. For example:

Linux and macOS

If you want double precision, you can specify :sin; if you want single precision, you can specify :sinf, as in -fimf-arch-consistency=true:sin or -fimf-arch-consistency=false:sqrtf.

Windows

If you want double precision, you can specify :sin; if you want single precision, you can specify :sinf, as in /Qimf-arch-consistency:true:sin or /Qimf-arch-consistency:false:sqrtf.

If you do not specify any function names, then the setting applies to all functions (and to all precisions). However, as soon as you specify an individual function name, the setting applies only to the function of corresponding precision. So, for example, sinf applies only to the single-precision sine function, sin applies only to the double-precision sine function, sinl applies only to the extended-precision sine function, etc.

The -fimf-arch-consistency (Linux* and macOS) and /Qimf-arch-consistency (Windows*) option may decrease run-time performance, but the option will provide bit-wise consistent results on all Intel® processors and compatible, non-Intel processors, regardless of micro-architecture. This option may not provide bit-wise consistent results between different architectures.

### Note

Many routines in libraries LIBM (Math Library) and SVML (Short Vector Math Library) are more highly optimized for Intel® microprocessors than for non-Intel microprocessors.

### Note

The standard Fortran names for the various math intrinsic functions do not match the math library names of the math intrinsic functions. You must find the actual math library name that is generated for the relevant Fortran math intrinsic.

One way to do this is to generate assembly code by using one of the following options:

Linux and macOS

-S

Windows

/Fa or /S

The assembly code will show the actual math library name.

For example, if you create a program that contains a call to SIN(x) where x is declared as REAL(KIND=4) and then use option S to produce assembly code for the program, the assembly code will show a call to sinf.

To ensure consistent results for the single-precision sine function, you should specify:

Linux and macOS

-fimf-arch-consistency=sinf

Windows

/Qimf-arch-consistency:sinf

### Note

This option only applies to host compilation. When offloading is enabled, it does not impact device-specific compilation. Offloading can only be enabled when using ifx.

Product and Performance Information
Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex. Notice revision #20201201

## IDE Equivalent

None

## Alternate Options

None

Parent topic: Floating-Point Options

## See Also

fimf-absolute-error, Qimf-absolute-error compiler option
fimf-accuracy-bits, Qimf-accuracy-bits compiler option
fimf-domain-exclusion, Qimf-domain-exclusion compiler option
fimf-max-error, Qimf-max-error compiler option
fimf-precision, Qimf-precision compiler option
fimf-use-svml_Qimf-use-svml compiler option