Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3  -  computes  all  eigenvalues  and, optionally, eigenvectors of a real symmetric
       matrix A

SYNOPSIS

       SUBROUTINE SSYEV( JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, INFO )

           CHARACTER     JOBZ, UPLO

           INTEGER       INFO, LDA, LWORK, N

           REAL          A( LDA, * ), W( * ), WORK( * )

PURPOSE

       SSYEV computes all eigenvalues and, optionally, eigenvectors of a real symmetric 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) REAL array, dimension (LDA, N)
                On entry, the symmetric 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) REAL array, dimension (N)
                If INFO = 0, the eigenvalues in ascending order.

        WORK    (workspace/output) REAL array, dimension (MAX(1,LWORK))
                On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

        LWORK   (input) INTEGER
                The length of the array WORK.  LWORK >= max(1,3*N-1).
                For optimal efficiency, LWORK >= (NB+2)*N,
                where NB is the blocksize for SSYTRD 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.

        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.

 LAPACK driver routine (version 3.2)        April 2011                             SSYEV(3lapack)