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
COMPZSpecifies computation of eigenvectors ('V') or not ('N')
NOrder of the matrix
DOn entry, the diagonal elements. On exit, the eigenvalues in ascending order
EOff-diagonal elements on entry; destroyed on exit
ZOn entry, if COMPZ = 'V', then Z is an N-by-N matrix. On exit, if COMPZ = 'V', Z contains the orthogonal matrix of eigenvectors
LDZLeading dimension of Z as declared in the calling subroutine
WORKWork array, dimension (max(1, 2*N-2)) if COMPZ = 'V', (max(1, 1)) otherwise
INFOINFO = 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.

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

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