Name

log - returns the natural logarithm of scalars and vectors

Synopsis

float  log(float a);
float1 log(float1 a);
float2 log(float2 a);
float3 log(float3 a);
float4 log(float4 a);

half   log(half a);
half1  log(half1 a);
half2  log(half2 a);
half3  log(half3 a);
half4  log(half4 a);

fixed  log(fixed a);
fixed1 log(fixed1 a);
fixed2 log(fixed2 a);
fixed3 log(fixed3 a);
fixed4 log(fixed4 a);

Parameters

a

Vector or scalar of which to determine the natural logarithm.

Description

Returns the natural logarithm a.

For vectors, the returned vector contains the natural logarithm of each element of the input vector.

Reference Implementation

float3 log(float3 a)
{
  float3 rv;
  int i;

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

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

Profile Support

log is fully supported in all profiles unless otherwise specified.

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

See Also

exp, log10, log2, pow