NAME
    log2 - returns the base-2 logarithm of scalars and vectors

SYNOPSIS
      float  log2(float a);
      float1 log2(float1 a);
      float2 log2(float2 a);
      float3 log2(float3 a);
      float4 log2(float4 a);
 
      half   log2(half a);
      half1  log2(half1 a);
      half2  log2(half2 a);
      half3  log2(half3 a);
      half4  log2(half4 a);
 
      fixed  log2(fixed a);
      fixed1 log2(fixed1 a);
      fixed2 log2(fixed2 a);
      fixed3 log2(fixed3 a);
      fixed4 log2(fixed4 a);

PARAMETERS
    a       Vector or scalar of which to determine the base-2 logarithm.

DESCRIPTION
    Returns the base-2 logarithm *a*.

    For vectors, the returned vector contains the base-2 logarithm of each
    element of the input vector.

REFERENCE IMPLEMENTATION
      float3 log2(float3 a)
      {
        float3 rv;
        int i;

        for (i=0; i<3; i++) {
          rv[i] = log2(a[i]);  // this is the ANSI C standard library log2()
        }
        return rv;
      }

    log2 is typically implemented with a native base-2 logarithm
    instruction.

PROFILE SUPPORT
    log2 is fully supported in all profiles unless otherwise specified.

    Support in the fp20 is limited to constant compile-time evaluation.

SEE ALSO
    the exp manpage, the log manpage, the log10 manpage, the pow manpage

