gjp_lapack::DSTEQR Interface Reference

Compute the eigenvalues and eigenvectors of a real symmetric tridiagonal matrix. More...

Public Member Functions
subroutine	dsteqr (COMPZ, N, D, E, Z, LDZ, WORK, INFO)

Detailed Description

Compute the eigenvalues and eigenvectors of a real symmetric tridiagonal matrix.

The DSTEQR subroutine computes all eigenvalues and, optionally, eigenvectors of a real, symmetric, tridiagonal matrix. It uses the implicit QL or QR method to do so.

More information on DSTEQR can be found in the LAPACK documentation.

Parameters

COMPZ	Specifies computation of eigenvectors ('V') or not ('N')
N	Order of the matrix
D	On entry, the diagonal elements. On exit, the eigenvalues in ascending order
E	Off-diagonal elements on entry; destroyed on exit
Z	On entry, if COMPZ = 'V', then Z is an N-by-N matrix. On exit, if COMPZ = 'V', Z contains the orthogonal matrix of eigenvectors
LDZ	Leading dimension of Z as declared in the calling subroutine
WORK	Work array, dimension (max(1, 2*N-2)) if COMPZ = 'V', (max(1, 1)) otherwise
INFO	INFO = 0: successful exit. INFO = K: the algorithm failed to find all the eigenvalues, no eigenvectors or eigenvectors of order K have been found

Definition at line 41 of file gjp_lapack.f90.

Member Function/Subroutine Documentation

dsteqr()

subroutine gjp_lapack::DSTEQR::dsteqr	(	character	COMPZ,
		integer	N,
		real(dp), dimension(*)	D,
		real(dp), dimension(*)	E,
		real(dp), dimension(ldz, *)	Z,
		integer	LDZ,
		real(dp), dimension(*)	WORK,
		integer	INFO
	)

Definition at line 41 of file gjp_lapack.f90.

        import :: dp
        character :: COMPZ
        integer :: N, LDZ, INFO
        real(dp) :: D(*), E(*), Z(LDZ, *), WORK(*)

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The documentation for this interface was generated from the following file:

• src/gjp_lapack.f90