code: @Override
      public boolean setA(DMatrixRMaj A) {
          if( A.numRows > maxRows || A.numCols > maxCols ) {
              setMaxSize(A.numRows,A.numCols);
          }
  
          _setA(A);
          if( !decomposer.decompose(A) )
              return false;
  
          Q.reshape(numRows,numRows, false);
          R.reshape(numRows,numCols, false);
          decomposer.getQ(Q,false);
          decomposer.getR(R,false);
  
          return true;
      }
docs: Performs QR decomposition on A
  
  @param A not modified.