claed0.f - Man Page
SRC/claed0.f
Synopsis
Functions/Subroutines
subroutine claed0 (qsiz, n, d, e, q, ldq, qstore, ldqs, rwork, iwork, info)
CLAED0 used by CSTEDC. Computes all eigenvalues and corresponding eigenvectors of an unreduced symmetric tridiagonal matrix using the divide and conquer method.
Function/Subroutine Documentation
subroutine claed0 (integer qsiz, integer n, real, dimension( * ) d, real, dimension( * ) e, complex, dimension( ldq, * ) q, integer ldq, complex, dimension( ldqs, * ) qstore, integer ldqs, real, dimension( * ) rwork, integer, dimension( * ) iwork, integer info)
CLAED0 used by CSTEDC. Computes all eigenvalues and corresponding eigenvectors of an unreduced symmetric tridiagonal matrix using the divide and conquer method.
Purpose:
Using the divide and conquer method, CLAED0 computes all eigenvalues of a symmetric tridiagonal matrix which is one diagonal block of those from reducing a dense or band Hermitian matrix and corresponding eigenvectors of the dense or band matrix.
- Parameters
QSIZ
QSIZ is INTEGER The dimension of the unitary matrix used to reduce the full matrix to tridiagonal form. QSIZ >= N if ICOMPQ = 1.
N
N is INTEGER The dimension of the symmetric tridiagonal matrix. N >= 0.
D
D is REAL array, dimension (N) On entry, the diagonal elements of the tridiagonal matrix. On exit, the eigenvalues in ascending order.
E
E is REAL array, dimension (N-1) On entry, the off-diagonal elements of the tridiagonal matrix. On exit, E has been destroyed.
Q
Q is COMPLEX array, dimension (LDQ,N) On entry, Q must contain an QSIZ x N matrix whose columns unitarily orthonormal. It is a part of the unitary matrix that reduces the full dense Hermitian matrix to a (reducible) symmetric tridiagonal matrix.
LDQ
LDQ is INTEGER The leading dimension of the array Q. LDQ >= max(1,N).
IWORK
IWORK is INTEGER array, the dimension of IWORK must be at least 6 + 6*N + 5*N*lg N ( lg( N ) = smallest integer k such that 2^k >= N )
RWORK
RWORK is REAL array, dimension (1 + 3*N + 2*N*lg N + 3*N**2) ( lg( N ) = smallest integer k such that 2^k >= N )
QSTORE
QSTORE is COMPLEX array, dimension (LDQS, N) Used to store parts of the eigenvector matrix when the updating matrix multiplies take place.
LDQS
LDQS is INTEGER The leading dimension of the array QSTORE. LDQS >= max(1,N).
INFO
INFO is INTEGER = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value. > 0: The algorithm failed to compute an eigenvalue while working on the submatrix lying in rows and columns INFO/(N+1) through mod(INFO,N+1).
- Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 143 of file claed0.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Referenced By
The man page claed0(3) is an alias of claed0.f(3).
Tue Nov 28 2023 12:08:41 Version 3.12.0 LAPACK