
NAMEzheev.f SYNOPSISFunctions/Subroutinessubroutine zheev (JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, RWORK, INFO) Function/Subroutine Documentationsubroutine zheev (characterJOBZ, characterUPLO, integerN, complex*16, dimension( lda, * )A, integerLDA, double precision, dimension( * )W, complex*16, dimension( * )WORK, integerLWORK, double precision, dimension( * )RWORK, integerINFO)ZHEEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for HE matrices Purpose:ZHEEV computes all eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A. JOBZ
Author:
JOBZ is CHARACTER*1 = 'N': Compute eigenvalues only; = 'V': Compute eigenvalues and eigenvectors.UPLO UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.N N is INTEGER The order of the matrix A. N >= 0.A A is COMPLEX*16 array, dimension (LDA, N) On entry, the Hermitian matrix A. If UPLO = 'U', the leading NbyN upper triangular part of A contains the upper triangular part of the matrix A. If UPLO = 'L', the leading NbyN lower triangular part of A contains the lower triangular part of the matrix A. On exit, if JOBZ = 'V', then if INFO = 0, A contains the orthonormal eigenvectors of the matrix A. If JOBZ = 'N', then on exit the lower triangle (if UPLO='L') or the upper triangle (if UPLO='U') of A, including the diagonal, is destroyed.LDA LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).W W is DOUBLE PRECISION array, dimension (N) If INFO = 0, the eigenvalues in ascending order.WORK WORK is COMPLEX*16 array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK.LWORK LWORK is INTEGER The length of the array WORK. LWORK >= max(1,2*N1). For optimal efficiency, LWORK >= (NB+1)*N, where NB is the blocksize for ZHETRD returned by ILAENV. If LWORK = 1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.RWORK RWORK is DOUBLE PRECISION array, dimension (max(1, 3*N2))INFO INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value > 0: if INFO = i, the algorithm failed to converge; i offdiagonal elements of an intermediate tridiagonal form did not converge to zero. Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011
Definition at line 140 of file zheev.f.
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