CXML
        	    
LAPACK version 3.0
zhegst(3)

PURPOSE
  ZHEGST - reduce a complex Hermitian-definite generalized eigenproblem to
  standard form

SYNTAX
  SUBROUTINE ZHEGST( ITYPE, UPLO, N, A, LDA, B, LDB, INFO )

      CHARACTER	     UPLO

      INTEGER	     INFO, ITYPE, LDA, LDB, N

      COMPLEX*16     A( LDA, * ), B( LDB, * )

DESCRIPTION
  ZHEGST reduces a complex Hermitian-definite generalized eigenproblem to
  standard form.  If ITYPE = 1, the problem is A*x = lambda*B*x,
  and A is overwritten by inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H)

  If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or
  B*A*x = lambda*x, and A is overwritten by U*A*U**H or L**H*A*L.

  B must have been previously factorized as U**H*U or L*L**H by ZPOTRF.

ARGUMENTS
  ITYPE	  (input) INTEGER
	  = 1: compute inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H);
	  = 2 or 3: compute U*A*U**H or L**H*A*L.

  UPLO	  (input) CHARACTER
	  = 'U':  Upper triangle of A is stored and B is factored as U**H*U;
	  = 'L':  Lower triangle of A is stored and B is factored as L*L**H.

  N	  (input) INTEGER
	  The order of the matrices A and B.  N >= 0.

  A	  (input/output) COMPLEX*16 array, dimension (LDA,N)
	  On entry, the Hermitian matrix A.  If UPLO = 'U', the leading N-
	  by-N upper triangular part of A contains the upper triangular part
	  of the matrix A, and the strictly lower triangular part of A is not
	  referenced.  If UPLO = 'L', the leading N-by-N lower triangular
	  part of A contains the lower triangular part of the matrix A, and
	  the strictly upper triangular part of A is not referenced.

	  On exit, if INFO = 0, the transformed matrix, stored in the same
	  format as A.

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

  B	  (input) COMPLEX*16 array, dimension (LDB,N)
	  The triangular factor from the Cholesky factorization of B, as
	  returned by ZPOTRF.

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

  INFO	  (output) INTEGER
	  = 0:	successful exit
	  < 0:	if INFO = -i, the i-th argument had an illegal value