code: @Override
      public ZMatrixRMaj getQ(ZMatrixRMaj Q , boolean compact ) {
          if( compact )
              Q = UtilDecompositons_ZDRM.checkIdentity(Q,numRows,minLength);
          else
              Q = UtilDecompositons_ZDRM.checkIdentity(Q,numRows,numRows);
  
          for( int j = minLength-1; j >= 0; j-- ) {
              QrHelperFunctions_ZDRM.extractHouseholderColumn(QR,j,numRows,j,u,0);
              QrHelperFunctions_ZDRM.rank1UpdateMultR(Q,u,0,gammas[j],j,j,numRows,v);
          }
  
          return Q;
      }
docs: Computes the Q matrix from the information stored in the QR matrix.  This
  operation requires about 4(m<sup>2</sup>n-mn<sup>2</sup>+n<sup>3</sup>/3) flops.
  
  @param Q The orthogonal Q matrix.