docs: public static double extractColumnAndMax( ZMatrixRMaj A ,
                                                int row0 , int row1 ,
                                                int col , double u[], int offsetU) {
          int indexU = (offsetU+row0)*2;
  
          // find the largest value in this column
          // this is used to normalize the column and mitigate overflow/underflow
          double max = 0;
  
          int indexA = A.getIndex(row0,col);
          double h[] = A.data;
  
          for( int i = row0; i < row1; i++, indexA += A.numCols*2 ) {
              // copy the householder vector to an array to reduce cache misses
              // big improvement on larger matrices and a relatively small performance hit on small matrices.
              double realVal = u[indexU++] = h[indexA];
              double imagVal = u[indexU++] = h[indexA+1];
  
              double magVal = realVal*realVal + imagVal*imagVal;
              if( max < magVal ) {
                  max = magVal;
              }
          }
          return Math.sqrt(max);
      }