code: public static void elementMult( DMatrix2x2 a , DMatrix2x2 b) {
          a.a11 *= b.a11; a.a12 *= b.a12;
          a.a21 *= b.a21; a.a22 *= b.a22;
      }
docs: <p>Performs an element by element multiplication operation:<br>
  <br>
  a<sub>ij</sub> = a<sub>ij</sub> * b<sub>ij</sub> <br>
  </p>
  @param a The left matrix in the multiplication operation. Modified.
  @param b The right matrix in the multiplication operation. Not modified.