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LAPACK version 3.0
chpev(3)

PURPOSE
  CHPEV - compute all the eigenvalues and, optionally, eigenvectors of a
  complex Hermitian matrix in packed storage

SYNTAX
  SUBROUTINE CHPEV( JOBZ, UPLO, N, AP, W, Z, LDZ, WORK, RWORK, INFO )

      CHARACTER	    JOBZ, UPLO

      INTEGER	    INFO, LDZ, N

      REAL	    RWORK( * ), W( * )

      COMPLEX	    AP( * ), WORK( * ), Z( LDZ, * )

DESCRIPTION
  CHPEV computes all the eigenvalues and, optionally, eigenvectors of a
  complex Hermitian matrix in packed storage.

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.

  AP	  (input/output) COMPLEX array, dimension (N*(N+1)/2)
	  On entry, the upper or lower triangle of the Hermitian matrix A,
	  packed columnwise in a linear array.	The j-th column of A is
	  stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2)
	  = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) =
	  A(i,j) for j<=i<=n.

	  On exit, AP is overwritten by values generated during the reduction
	  to tridiagonal form.	If UPLO = 'U', the diagonal and first
	  superdiagonal of the tridiagonal matrix T overwrite the
	  corresponding elements of A, and if UPLO = 'L', the diagonal and
	  first subdiagonal of T overwrite the corresponding elements of A.

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

  Z	  (output) COMPLEX array, dimension (LDZ, N)
	  If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal
	  eigenvectors of the matrix A, with the i-th column of Z holding the
	  eigenvector associated with W(i).  If JOBZ = 'N', then Z is not
	  referenced.

  LDZ	  (input) INTEGER
	  The leading dimension of the array Z.	 LDZ >= 1, and if JOBZ = 'V',
	  LDZ >= max(1,N).

  WORK	  (workspace) COMPLEX array, dimension (max(1, 2*N-1))

  RWORK	  (workspace) REAL 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.