SRC/sspgst.f(3)

NAME
SRC/sspgst.f

SYNOPSIS

  Functions/Subroutines
subroutine sspgst (itype, uplo, n, ap, bp, info)
SSPGST

Function/Subroutine Documentation

  subroutine sspgst (integer itype, character uplo, integer n, real, dimension( * ) ap, real, dimension( * ) bp, integer info)

SSPGST

Purpose:

    !>
    !> SSPGST 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 SPPTRF.
    !>

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 REAL 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 REAL 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 SPPTRF.
    !>

    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 sspgst.f.

Author

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