Returns the base-2 logarithm of the specified value.

ret log2(x)





[in] The specified value.


Return Value

The base-2 logarithm of the x parameter. If the x parameter is negative, this function returns indefinite. If the x parameter is 0, this function returns +INF.

Type Description

Name Template Type Component Type Size
xscalar, vector, or matrix float any
retsame as input x float same dimension(s) as input x


Minimum Shader Model

This function is supported in the following shader models.

Shader ModelSupported
Shader Model 2 (DirectX HLSL) and higher shader modelsyes
Shader Model 1 (DirectX HLSL) yes (vs_1_1 only)


See also

Intrinsic Functions (DirectX HLSL)