NAME

       zhegst.f -

SYNOPSIS

   Functions/Subroutines
       subroutine zhegst (ITYPE, UPLO, N, A, LDA, B, LDB, INFO)
           ZHEGST

Function/Subroutine Documentation

   subroutine zhegst (integerITYPE, characterUPLO, integerN, complex*16, dimension( lda, * )A,
       integerLDA, complex*16, dimension( ldb, * )B, integerLDB, integerINFO)
       ZHEGST

       Purpose:

            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.

       Parameters:
           ITYPE

                     ITYPE is 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

                     UPLO is CHARACTER*1
                     = '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

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

           A

                     A is 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

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

           B

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

           LDB

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

           INFO

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

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           September 2012

       Definition at line 128 of file zhegst.f.

Author

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