DSYGS2 man page on IRIX

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DSYGS2(3F)							    DSYGS2(3F)

NAME
     DSYGS2 - reduce a real symmetric-definite generalized eigenproblem to
     standard form

SYNOPSIS
     SUBROUTINE DSYGS2( ITYPE, UPLO, N, A, LDA, B, LDB, INFO )

	 CHARACTER	UPLO

	 INTEGER	INFO, ITYPE, LDA, LDB, N

	 DOUBLE		PRECISION A( LDA, * ), B( LDB, * )

PURPOSE
     DSYGS2 reduces a real symmetric-definite generalized eigenproblem to
     standard form.

     If ITYPE = 1, the problem is A*x = lambda*B*x,
     and A is overwritten by inv(U')*A*inv(U) or inv(L)*A*inv(L')

     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` or L'*A*L.

     B must have been previously factorized as U'*U or L*L' by DPOTRF.

ARGUMENTS
     ITYPE   (input) INTEGER
	     = 1: compute inv(U')*A*inv(U) or inv(L)*A*inv(L');
	     = 2 or 3: compute U*A*U' or L'*A*L.

     UPLO    (input) CHARACTER
	     Specifies whether the upper or lower triangular part of the
	     symmetric matrix A is stored, and how B has been factorized.  =
	     'U':  Upper triangular
	     = 'L':  Lower triangular

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

     A	     (input/output) DOUBLE PRECISION array, dimension (LDA,N)
	     On entry, the symmetric matrix A.	If UPLO = 'U', the leading n
	     by n upper triangular part of A contains the upper triangular
	     part of the matrix A, and the strictly lower triangular part of A
	     is not referenced.	 If UPLO = 'L', the leading n by n lower
	     triangular part of A contains the lower triangular part of the
	     matrix A, and the strictly upper triangular part of A is not
	     referenced.

	     On exit, if INFO = 0, the transformed matrix, stored in the same
	     format as A.

									Page 1

DSYGS2(3F)							    DSYGS2(3F)

     LDA     (input) INTEGER
	     The leading dimension of the array A.  LDA >= max(1,N).

     B	     (input) DOUBLE PRECISION array, dimension (LDB,N)
	     The triangular factor from the Cholesky factorization of B, as
	     returned by DPOTRF.

     LDB     (input) INTEGER
	     The leading dimension of the array B.  LDB >= max(1,N).

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

									Page 2

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