
SSPGST(l) ) SSPGST(l)
NAME
SSPGST  reduce a real symmetricdefinite generalized eigenproblem to standard form, using
packed storage
SYNOPSIS
SUBROUTINE SSPGST( ITYPE, UPLO, N, AP, BP, INFO )
CHARACTER UPLO
INTEGER INFO, ITYPE, N
REAL AP( * ), BP( * )
PURPOSE
SSPGST reduces a real symmetricdefinite 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.
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) 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 jth column of A is stored in the array AP as follows: if
UPLO = 'U', AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i +
(j1)*(2nj)/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) 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 (output) INTEGER
= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
LAPACK version 3.0 15 June 2000 SSPGST(l) 
