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NAME
     dspgst - reduce a real symmetric-definite generalized eigen-
     problem to standard form, using packed storage

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

     CHARACTER UPLO

     INTEGER INFO, ITYPE, N

     DOUBLE PRECISION AP( * ), BP( * )



     #include <sunperf.h>

     void dspgst(int itype, char uplo, int n, double *dap, double
               *bp, int *info) ;

PURPOSE
     DSPGST reduces a real symmetric-definite generalized  eigen-
     problem 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.


ARGUMENTS
     ITYPE     (input) 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      (input) CHARACTER
               = '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         (input) INTEGER
               The order of the matrices A and B.  N >= 0.

     AP        (input/output) DOUBLE PRECISION  array,  dimension
               (N*(N+1)/2)
               On entry, the upper or lower triangle of the  sym-
               metric  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)   DOUBLE   PRECISION   array,    dimension
               (N*(N+1)/2)
               The triangular factor from the Cholesky factoriza-
               tion  of  B,  stored  in  the same format as A, as
               returned by DPPTRF.

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

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