Method evalTo

include/Eigen/src/SparseQR/SparseQR.h:592–626

  // Assign to a vector
  template <typename DesType>
  void evalTo(DesType& res) const {
    Index m = m_qr.rows();
    Index n = m_qr.cols();
    Index diagSize = (std::min)(m, n);
    res = m_other;
    if (m_transpose) {
      eigen_assert(m_qr.m_Q.rows() == m_other.rows() && "Non conforming object sizes");
      // Compute res = Q' * other column by column
      for (Index j = 0; j < res.cols(); j++) {
        for (Index k = 0; k < diagSize; k++) {
          Scalar tau = Scalar(0);
          tau = m_qr.m_Q.col(k).dot(res.col(j));
          if (tau == Scalar(0)) continue;
          tau = tau * m_qr.m_hcoeffs(k);
          res.col(j) -= tau * m_qr.m_Q.col(k);
        }
      }
    } else {
      eigen_assert(m_qr.matrixQ().cols() == m_other.rows() && "Non conforming object sizes");

      res.conservativeResize(rows(), cols());

      // Compute res = Q * other column by column
      for (Index j = 0; j < res.cols(); j++) {
        Index start_k = internal::is_identity<Derived>::value ? numext::mini(j, diagSize - 1) : diagSize - 1;
        for (Index k = start_k; k >= 0; k--) {
          Scalar tau = Scalar(0);
          tau = m_qr.m_Q.col(k).dot(res.col(j));
          if (tau == Scalar(0)) continue;
          tau = tau * numext::conj(m_qr.m_hcoeffs(k));
          res.col(j) -= tau * m_qr.m_Q.col(k);
        }
      }
    }
  }

  const SparseQRType& m_qr;
  const Derived& m_other;