code: public static void elementDiv( 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 division operation:<br>
  <br>
  a<sub>ij</sub> = a<sub>ij</sub> / b<sub>ij</sub> <br>
  </p>
  @param a The left matrix in the division operation. Modified.
  @param b The right matrix in the division operation. Not modified.