zheev(3F)

NAME
     ZHEEV - compute all eigenvalues and, optionally, eigenvectors of a
     complex Hermitian matrix A

SYNOPSIS
     SUBROUTINE ZHEEV( JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, RWORK, INFO )

         CHARACTER     JOBZ, UPLO

         INTEGER       INFO, LDA, LWORK, N

         DOUBLE        PRECISION RWORK( * ), W( * )

         COMPLEX*16    A( LDA, * ), WORK( * )

PURPOSE
     ZHEEV computes all eigenvalues and, optionally, eigenvectors of a complex
     Hermitian matrix A.


ARGUMENTS
     JOBZ    (input) CHARACTER*1
             = 'N':  Compute eigenvalues only;
             = 'V':  Compute eigenvalues and eigenvectors.

     UPLO    (input) CHARACTER*1
             = 'U':  Upper triangle of A is stored;
             = 'L':  Lower triangle of A is stored.

     N       (input) INTEGER
             The order of the matrix A.  N >= 0.

     A       (input/output) COMPLEX*16 array, dimension (LDA, N)
             On entry, the Hermitian matrix A.  If UPLO = 'U', the leading N-
             by-N upper triangular part of A contains the upper triangular
             part of the matrix A.  If UPLO = 'L', the leading N-by-N 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     (input) INTEGER
             The leading dimension of the array A.  LDA >= max(1,N).

     W       (output) DOUBLE PRECISION array, dimension (N)
             If INFO = 0, the eigenvalues in ascending order.

     WORK    (workspace/output) COMPLEX*16 array, dimension (LWORK)
             On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
     LWORK   (input) INTEGER
             The length of the array WORK.  LWORK >= max(1,2*N-1).  For
             optimal efficiency, LWORK >= (NB+1)*N, where NB is the blocksize
             for ZHETRD returned by ILAENV.

     RWORK   (workspace) DOUBLE PRECISION array, dimension (max(1, 3*N-2))

     INFO    (output) INTEGER
             = 0:  successful exit
             < 0:  if INFO = -i, the i-th argument had an illegal value
             > 0:  if INFO = i, the algorithm failed to converge; i off-
             diagonal elements of an intermediate tridiagonal form did not
             converge to zero.