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RedHat 9 (Linux i386) - man page for dspgst (redhat section l)

DSPGST(l)					)					DSPGST(l)

NAME
       DSPGST - reduce a real symmetric-definite generalized eigenproblem 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( * )

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.

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

LAPACK version 3.0			   15 June 2000 				DSPGST(l)


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