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dsygv.f(3)				      LAPACK				       dsygv.f(3)

NAME
       dsygv.f -

SYNOPSIS
   Functions/Subroutines
       subroutine dsygv (ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK, LWORK, INFO)
	   DSYGST

Function/Subroutine Documentation
   subroutine dsygv (integerITYPE, characterJOBZ, characterUPLO, integerN, double precision,
       dimension( lda, * )A, integerLDA, double precision, dimension( ldb, * )B, integerLDB,
       double precision, dimension( * )W, double precision, dimension( * )WORK, integerLWORK,
       integerINFO)
       DSYGST

       Purpose:

	    DSYGV computes all the eigenvalues, and optionally, the eigenvectors
	    of a real generalized symmetric-definite eigenproblem, of the form
	    A*x=(lambda)*B*x,  A*Bx=(lambda)*x,  or B*A*x=(lambda)*x.
	    Here A and B are assumed to be symmetric and B is also
	    positive definite.

       Parameters:
	   ITYPE

		     ITYPE is INTEGER
		     Specifies the problem type to be solved:
		     = 1:  A*x = (lambda)*B*x
		     = 2:  A*B*x = (lambda)*x
		     = 3:  B*A*x = (lambda)*x

	   JOBZ

		     JOBZ is CHARACTER*1
		     = 'N':  Compute eigenvalues only;
		     = 'V':  Compute eigenvalues and eigenvectors.

	   UPLO

		     UPLO is CHARACTER*1
		     = 'U':  Upper triangles of A and B are stored;
		     = 'L':  Lower triangles of A and B are stored.

	   N

		     N is INTEGER
		     The order of the matrices A and B.  N >= 0.

	   A

		     A is 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
		     matrix Z of eigenvectors.	The eigenvectors are normalized
		     as follows:
		     if ITYPE = 1 or 2, Z**T*B*Z = I;
		     if ITYPE = 3, Z**T*inv(B)*Z = I.
		     If JOBZ = 'N', then on exit the upper triangle (if UPLO='U')
		     or the lower triangle (if UPLO='L') of A, including the
		     diagonal, is destroyed.

	   LDA

		     LDA is INTEGER
		     The leading dimension of the array A.  LDA >= max(1,N).

	   B

		     B is DOUBLE PRECISION array, dimension (LDB, N)
		     On entry, the symmetric positive definite matrix B.
		     If UPLO = 'U', the leading N-by-N upper triangular part of B
		     contains the upper triangular part of the matrix B.
		     If UPLO = 'L', the leading N-by-N lower triangular part of B
		     contains the lower triangular part of the matrix B.

		     On exit, if INFO <= N, the part of B containing the matrix is
		     overwritten by the triangular factor U or L from the Cholesky
		     factorization B = U**T*U or B = L*L**T.

	   LDB

		     LDB is INTEGER
		     The leading dimension of the array B.  LDB >= max(1,N).

	   W

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

	   WORK

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

	   LWORK

		     LWORK is 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.

		     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

		     INFO is INTEGER
		     = 0:  successful exit
		     < 0:  if INFO = -i, the i-th argument had an illegal value
		     > 0:  DPOTRF or DSYEV returned an error code:
			<= N:  if INFO = i, DSYEV failed to converge;
			       i off-diagonal elements of an intermediate
			       tridiagonal form did not converge to zero;
			> N:   if INFO = N + i, for 1 <= i <= N, then the leading
			       minor of order i of B is not positive definite.
			       The factorization of B could not be completed and
			       no eigenvalues or eigenvectors were computed.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 175 of file dsygv.f.

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

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