code: public static void divide( DMatrix3 a , double alpha ) {
          a.a1 /= alpha;
          a.a2 /= alpha;
          a.a3 /= alpha;
      }
docs: <p>
  Performs an in-place element by element scalar division. Scalar denominator.<br>
  <br>
  a<sub>i</sub> = a<sub>i</sub>/&alpha;
  </p>
  
  @param a The vector whose elements are to be divided.  Modified.
  @param alpha the amount each element is divided by.