code: public Matrix3 set (
          double m00, double m10, double m20,
          double m01, double m11, double m21,
          double m02, double m12, double m22) {
          this.m00 = m00; this.m01 = m01; this.m02 = m02;
          this.m10 = m10; this.m11 = m11; this.m12 = m12;
          this.m20 = m20; this.m21 = m21; this.m22 = m22;
          return this;
      }
docs: Sets all of the matrix's components at once.
  
  @return a reference to this matrix, for chaining.