claed0.f (3)  Linux Manuals
NAME
claed0.f 
SYNOPSIS
Functions/Subroutines
subroutine claed0 (QSIZ, N, D, E, Q, LDQ, QSTORE, LDQS, RWORK, IWORK, INFO)
CLAED0 used by sstedc. Computes all eigenvalues and corresponding eigenvectors of an unreduced symmetric tridiagonal matrix using the divide and conquer method.
Function/Subroutine Documentation
subroutine claed0 (integerQSIZ, integerN, real, dimension( * )D, real, dimension( * )E, complex, dimension( ldq, * )Q, integerLDQ, complex, dimension( ldqs, * )QSTORE, integerLDQS, real, dimension( * )RWORK, integer, dimension( * )IWORK, integerINFO)
CLAED0 used by sstedc. 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.
NN is INTEGER The dimension of the symmetric tridiagonal matrix. N >= 0.
DD is REAL array, dimension (N) On entry, the diagonal elements of the tridiagonal matrix. On exit, the eigenvalues in ascending order.
EE is REAL array, dimension (N1) On entry, the offdiagonal elements of the tridiagonal matrix. On exit, E has been destroyed.
QQ 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.
LDQLDQ is INTEGER The leading dimension of the array Q. LDQ >= max(1,N).
IWORKIWORK 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 )
RWORKRWORK is REAL array, dimension (1 + 3*N + 2*N*lg N + 3*N**2) ( lg( N ) = smallest integer k such that 2^k >= N )
QSTOREQSTORE is COMPLEX array, dimension (LDQS, N) Used to store parts of the eigenvector matrix when the updating matrix multiplies take place.
LDQSLDQS is INTEGER The leading dimension of the array QSTORE. LDQS >= max(1,N).
INFOINFO is INTEGER = 0: successful exit. < 0: if INFO = i, the ith 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.
Date:
 September 2012
Definition at line 145 of file claed0.f.
Author
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