docs: @Override
      public DMatrixRMaj getR(DMatrixRMaj R, boolean compact) {
          if( compact ) {
              R = UtilDecompositons_DDRM.checkZerosLT(R,minLength,numCols);
          } else {
              R = UtilDecompositons_DDRM.checkZerosLT(R,numRows,numCols);
          }
  
          for( int j = 0; j < numCols; j++ ) {
              double colR[] = dataQR[j];
              int l = Math.min(j,numRows-1);
              for( int i = 0; i <= l; i++ ) {
                  double val = colR[i];
                  R.set(i,j,val);
              }
          }
  
          return R;
      }