CHPGST(3f)               LAPACK routine (version 3.1)               CHPGST(3f)



NAME
       CHPGST - a complex Hermitian-definite generalized eigenproblem to
       standard form, using packed storage

SYNOPSIS
       SUBROUTINE CHPGST( ITYPE, UPLO, N, AP, BP, INFO )

           CHARACTER      UPLO

           INTEGER        INFO, ITYPE, N

           COMPLEX        AP( * ), BP( * )

PURPOSE
       CHPGST reduces a complex Hermitian-definite generalized eigenproblem to
       standard form, using packed storage.

       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 CPPTRF.


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*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       (input) INTEGER
               The order of the matrices A and B.  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)*(2n-j)/2) = A(i,j) for j<=i<=n.

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

       BP      (input) COMPLEX array, dimension (N*(N+1)/2)
               The triangular factor from the Cholesky factorization of B,
               stored in the same format as A, as returned by CPPTRF.

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



 LAPACK routine (version 3.1)    November 2006                      CHPGST(3f)
