Edit

fma

  • Article

Returns the double-precision fused multiply-addition of a * b + c.

ret fma(double a, b, c);

Parameters

a

[in] The first value in the fused multiply-addition.

b

[in] The second value in the fused multiply-addition.

c

[in] The third value in the fused multiply-addition.

Return Value

The double-precision fused multiply-addition of parameters a * b + c. The returned value must be accurate to 0.5 units of least precision (ULP).

Remarks

The fma intrinsic must support NaNs, INFs, and Denorms.

To use the fma intrinsic in your shader code, call the ID3D11Device::CheckFeatureSupport method with D3D11_FEATURE_D3D11_OPTIONS to verify that the Direct3D device supports the ExtendedDoublesShaderInstructions feature option. The fma intrinsic requires a WDDM 1.2 display driver, and all WDDM 1.2 display drivers must support fma. If your app creates a rendering device with feature level 11.0 or 11.1 and the compilation target is shader model 5 or later, the HLSL source code can use the fma intrinsic.

Type Description

Name Template Type Component Type Size
a scalar, vector, or matrix double any
b same as input a double same dimensions as input a
c same as input a double same dimensions as input a
ret same as input a double same dimensions as input a

Minimum Shader Model

This function is supported in the following shader models.

Shader Model Supported
Shader model 5 or later yes

Requirements

Requirement Value
Minimum supported client
 Windows 8 [desktop apps | UWP apps]
Minimum supported server
 Windows Server 2012 [desktop apps | UWP apps]
Header
Corecrt_math.h

See also

Intrinsic Functions