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zhpevd.f(3)				      LAPACK				      zhpevd.f(3)

NAME
       zhpevd.f -

SYNOPSIS
   Functions/Subroutines
       subroutine zhpevd (JOBZ, UPLO, N, AP, W, Z, LDZ, WORK, LWORK, RWORK, LRWORK, IWORK,
	   LIWORK, INFO)
	    ZHPEVD computes the eigenvalues and, optionally, the left and/or right eigenvectors
	   for OTHER matrices

Function/Subroutine Documentation
   subroutine zhpevd (characterJOBZ, characterUPLO, integerN, complex*16, dimension( * )AP,
       double precision, dimension( * )W, complex*16, dimension( ldz, * )Z, integerLDZ,
       complex*16, dimension( * )WORK, integerLWORK, double precision, dimension( * )RWORK,
       integerLRWORK, integer, dimension( * )IWORK, integerLIWORK, integerINFO)
	ZHPEVD computes the eigenvalues and, optionally, the left and/or right eigenvectors for
       OTHER matrices

       Purpose:

	    ZHPEVD computes all the eigenvalues and, optionally, eigenvectors of
	    a complex Hermitian matrix A in packed storage.  If eigenvectors are
	    desired, it uses a divide and conquer algorithm.

	    The divide and conquer algorithm makes very mild assumptions about
	    floating point arithmetic. It will work on machines with a guard
	    digit in add/subtract, or on those binary machines without guard
	    digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or
	    Cray-2. It could conceivably fail on hexadecimal or decimal machines
	    without guard digits, but we know of none.

       Parameters:
	   JOBZ

		     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.

	   AP

		     AP is COMPLEX*16 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

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

	   Z

		     Z is COMPLEX*16 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

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

	   WORK

		     WORK is COMPLEX*16 array, dimension (MAX(1,LWORK))
		     On exit, if INFO = 0, WORK(1) returns the required LWORK.

	   LWORK

		     LWORK is INTEGER
		     The dimension of array WORK.
		     If N <= 1, 	      LWORK must be at least 1.
		     If JOBZ = 'N' and N > 1, LWORK must be at least N.
		     If JOBZ = 'V' and N > 1, LWORK must be at least 2*N.

		     If LWORK = -1, then a workspace query is assumed; the routine
		     only calculates the required sizes of the WORK, RWORK and
		     IWORK arrays, returns these values as the first entries of
		     the WORK, RWORK and IWORK arrays, and no error message
		     related to LWORK or LRWORK or LIWORK is issued by XERBLA.

	   RWORK

		     RWORK is DOUBLE PRECISION array,
						    dimension (LRWORK)
		     On exit, if INFO = 0, RWORK(1) returns the required LRWORK.

	   LRWORK

		     LRWORK is INTEGER
		     The dimension of array RWORK.
		     If N <= 1, 	      LRWORK must be at least 1.
		     If JOBZ = 'N' and N > 1, LRWORK must be at least N.
		     If JOBZ = 'V' and N > 1, LRWORK must be at least
			       1 + 5*N + 2*N**2.

		     If LRWORK = -1, then a workspace query is assumed; the
		     routine only calculates the required sizes of the WORK, RWORK
		     and IWORK arrays, returns these values as the first entries
		     of the WORK, RWORK and IWORK arrays, and no error message
		     related to LWORK or LRWORK or LIWORK is issued by XERBLA.

	   IWORK

		     IWORK is INTEGER array, dimension (MAX(1,LIWORK))
		     On exit, if INFO = 0, IWORK(1) returns the required LIWORK.

	   LIWORK

		     LIWORK is INTEGER
		     The dimension of array IWORK.
		     If JOBZ  = 'N' or N <= 1, LIWORK must be at least 1.
		     If JOBZ  = 'V' and N > 1, LIWORK must be at least 3 + 5*N.

		     If LIWORK = -1, then a workspace query is assumed; the
		     routine only calculates the required sizes of the WORK, RWORK
		     and IWORK arrays, returns these values as the first entries
		     of the WORK, RWORK and IWORK arrays, and no error message
		     related to LWORK or LRWORK or LIWORK is issued by XERBLA.

	   INFO

		     INFO is 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.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 201 of file zhpevd.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      zhpevd.f(3)
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