code: public static double normF( ZMatrixRMaj a ) {
          double total = 0;
  
          double scale = CommonOps_ZDRM.elementMaxAbs(a);
  
          if( scale == 0.0 )
              return 0.0;
  
          final int size = a.getDataLength();
  
          for( int i = 0; i < size; i += 2 ) {
              double real = a.data[i]/scale;
              double imag = a.data[i+1]/scale;
  
              total += real*real + imag*imag;
          }
  
          return scale* Math.sqrt(total);
      }
docs: <p>
  Computes the Frobenius matrix norm:<br>
  <br>
  normF = Sqrt{  &sum;<sub>i=1:m</sub> &sum;<sub>j=1:n</sub> { a<sub>ij</sub><sup>2</sup>}   }
  </p>
  <p>
  This is equivalent to the element wise p=2 norm.
  </p>
  
  @param a The matrix whose norm is computed.  Not modified.
  @return The norm's value.