chpgst(3S)

NAME
     CHPGST - reduce 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( * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

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
             = '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

SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

     This man page is available only online.