dsyev man page on IRIX

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DSYEV(3F)							     DSYEV(3F)

NAME
     DSYEV - compute all eigenvalues and, optionally, eigenvectors of a real
     symmetric matrix A

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

	 CHARACTER     JOBZ, UPLO

	 INTEGER       INFO, LDA, LWORK, N

	 DOUBLE	       PRECISION A( LDA, * ), W( * ), WORK( * )

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

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

									Page 1

DSYEV(3F)							     DSYEV(3F)

     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 DSYTRD returned by ILAENV.

     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.

									Page 2

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