1.2. Orthogonalization and Rayleigh-Ritz

void chase::Chase::QR(std::size_t fixednev, Base<T> cond) = 0

This member function performs a QR factorization with an explicit construction of the unitary matrix Q.

CholQR is used in default. Optionally, user can decide to use Househoulder QR.

Parameters

• fixednev: total number of converged eigenpairs before this time QR factorization.

void chase::Chase::RR(Base<T> *ritzv, std::size_t block) = 0

This function performs the Rayleigh-Ritz projection, which projects the eigenproblem to be a small one, then solves the small problem and reconstructs the eigenvectors.

Parameters

• ritzv: a pointer to the array which stores the computed eigenvalues.

• block: the number of non-converged eigenpairs, which determines the size of small eigenproblem.