code: public static double fastElementP(DMatrixD1 A , double p ) {
          if( p == 2 ) {
              return fastNormF(A);
          } else {
              double total = 0;
  
              int size = A.getNumElements();
  
              for( int i = 0; i < size; i++ ) {
                  double a = A.get(i);
  
                  total += Math.pow(Math.abs(a),p);
              }
  
              return Math.pow(total,1.0/p);
          }
      }
docs: Same as {@link #elementP} but runs faster by not mitigating overflow/underflow related problems.
  
  @param A Matrix. Not modified.
  @param p p value.
  @return The norm's value.