SRC/dspgst.f(3)            Library Functions Manual            SRC/dspgst.f(3)

NAME
       SRC/dspgst.f

SYNOPSIS
   Functions/Subroutines
       subroutine dspgst (itype, uplo, n, ap, bp, info)
           DSPGST

Function/Subroutine Documentation
   subroutine dspgst (integer itype, character uplo, integer n, double
       precision, dimension( * ) ap, double precision, dimension( * ) bp,
       integer info)
       DSPGST

       Purpose:


            DSPGST reduces a real symmetric-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**T)*A*inv(U) or inv(L)*A*inv(L**T)

            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**T or L**T*A*L.

            B must have been previously factorized as U**T*U or L*L**T by DPPTRF.

       Parameters
           ITYPE

                     ITYPE is INTEGER
                     = 1: compute inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T);
                     = 2 or 3: compute U*A*U**T or L**T*A*L.

           UPLO

                     UPLO is CHARACTER*1
                     = 'U':  Upper triangle of A is stored and B is factored as
                             U**T*U;
                     = 'L':  Lower triangle of A is stored and B is factored as
                             L*L**T.

           N

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

           AP

                     AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
                     On entry, the upper or lower triangle of the symmetric 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

                     BP is DOUBLE PRECISION 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 DPPTRF.

           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.

       Definition at line 112 of file dspgst.f.

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

LAPACK                          Version 3.12.0                 SRC/dspgst.f(3)