# fimf-domain-exclusion, Qimf-domain-exclusion

Indicates the input arguments domain on which math functions must provide correct results. This content is specific to C++; it does not apply to DPC++.

## Syntax

Linux: | -fimf-domain-exclusion=classlist[:funclist]

Windows: | /Qimf-domain-exclusion:classlist[:funclist]

## Arguments

- classlist | Is one of the following: One or more of the following floating-point value classes you can exclude from the function domain without affecting the correctness of your program. The supported class names are:
  extremes | This class is for values which do not lie within the usual domain of arguments for a given function.
  nans | This means "x=Nan".
  infinities | This means "x=infinities".
  denormals | This means "x=denormal".
  zeros | This means "x=0".
  Each classlist element corresponds to a power of two. The exclusion attribute is the logical or of the associated powers of two (that is, a bitmask). The following shows the current mapping from classlist mnemonics to numerical values:
  extremes | 1
  nans | 2
  infinities | 4
  denormals | 8
  zeros | 16
  none | 0
  all | 31
  common | 15
  other combinations | bitwise OR of the used values
- You must specify the integer value that corresponds to the class that you want to exclude. Note that on excluded values, unexpected results may occur. One of the following short-hand tokens:
  none | This means that none of the supported classes are excluded from the domain. To indicate this token, specify 0, as in -fimf-domain-exclusion=0 (or /Qimf-domain-exclusion:0).
  all | This means that all of the supported classes are excluded from the domain. To indicate this token, specify 31, as in -fimf-domain-exclusion=31 (or /Qimf-domain-exclusion:31).
  common | This is the same as specifying extremes,nans,infinities,denormals. To indicate this token, specify 15 (1 + 2+ 4 + 8), as in -fimf-domain-exclusion=15 (or /Qimf-domain-exclusion:15)
funclist | Is an optional list of one or more math library functions to which the attribute should be applied. 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-domain-exclusion=4:sin,sinf (or /Qimf-domain-exclusion:4:sin,sinf) to specify infinities 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-domain-exclusion=4 or /Qimf-domain-exclusion:4 -fimf-domain-exclusion=5:/,powf or /Qimf-domain-exclusion:5:/,powf -fimf-domain-exclusion=23:log,logf,/,sin,cosf or /Qimf-domain-exclusion:23:log,logf,/,sin,cosf If you don't specify argument funclist, the domain restrictions apply to all math library functions.

## Default

Zero ("0") | The compiler uses default heuristics when calling math library functions.

## Description

This option indicates the input arguments domain on which math functions must provide correct results. It specifies that your program will function correctly if the functions specified in funclist do not produce standard conforming results on the number classes.

This option can affect run-time performance and the accuracy of results. As more classes are excluded, faster code sequences can be used.

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, if you want double precision, you can specify :sin; if you want single precision, you can specify :sinf, as in -fimf-domain-exclusion=denormals:sin or /Qimf-domain-exclusion:denormals:sin, or -fimf-domain-exclusion=extremes:sqrtf or /Qimf-domain-exclusion:extremes: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.

### 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.

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

## Example

Consider the following single-precision sequence for function exp2f:

Operation: | y = exp2f(x)
Accuracy: | 1.014 ulp
Instructions: | 4 (2 without fix-up)

The following shows the 2-instruction sequence without the fix-up:

    vcvtfxpntps2dq  zmm1 {k1}, zmm0, 0x50      // zmm1 <-- rndToInt(2^24 * x)
    vexp223ps       zmm1 {k1}, zmm1            // zmm1 <-- exp2(x)

However, the above 2-instruction sequence will not correctly process NaNs. To process Nans correctly, the following fix-up must be included following the above instruction sequence:

    vpxord          zmm2, zmm2, zmm2             // zmm2 <-- 0
    vfixupnanps     zmm1 {k1}, zmm0, zmm2 {aaaa} // zmm1 <-- QNaN(x) if x is NaN <F>

If the `vfixupnanps` instruction is not included, the sequence correctly processes any arguments except NaN values. For example, the following options generate the 2-instruction sequence:

    -fimf-domain-exclusion=2:exp2f      <- NaN’s are excluded (2 corresponds to NaNs)
    -fimf-domain-exclusion=6:exp2f      <- NaN’s and infinities are excluded (4 corresponds to infinities; 2 + 4 = 6)
    -fimf-domain-exclusion=7:exp2f      <- NaN’s, infinities, and extremes are excluded (1 corresponds to extremes; 2 + 4 + 1 = 7)
    -fimf-domain-exclusion=15:exp2f     <- NaN’s, infinities, extremes, and denormals are excluded (8 corresponds to denormals;  2 + 4 + 1 + 8=15)

If the `vfixupnanps` instruction is included, the sequence correctly processes any arguments including NaN values. For example, the following options generate the 4-instruction sequence:

    -fimf-domain-exclusion=1:exp2f      <- only extremes are excluded (1 corresponds to extremes)
    -fimf-domain-exclusion=4:exp2f      <- only infinities are excluded (4 corresponds to infinities)
    -fimf-domain-exclusion=8:exp2f      <- only denormals are excluded (8 corresponds to denormals)
    -fimf-domain-exclusion=13:exp2f     <- only extremes, infinities and denormals are excluded (1 + 4 + 8 = 13)

Parent topic: Floating-Point Options

## See Also

fimf-absolute-error, Qimf-absolute-error compiler option
fimf-accuracy-bits, Qimf-accuracy-bits compiler option
fimf-arch-consistency, Qimf-arch-consistency compiler option
fimf-max-error, Qimf-max-error compiler option
fimf-precision, Qimf-precision compiler option
fimf-use-svml_Qimf-use-svml compiler option