code: public Matrix3 set (IMatrix3 other) {
          return set(other.m00(), other.m10(), other.m20(),
                     other.m01(), other.m11(), other.m21(),
                     other.m02(), other.m12(), other.m22());
      }
docs: Copies the contents of another matrix.
  
  @return a reference to this matrix, for chaining.