dsygs2(3) [centos man page]

dsygs2.f(3)							      LAPACK							       dsygs2.f(3)

NAME

       dsygs2.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dsygs2 (ITYPE, UPLO, N, A, LDA, B, LDB, INFO)
	   DSYGS2 reduces a symmetric definite generalized eigenproblem to standard form, using the factorization results obtained from spotrf
	   (unblocked algorithm).

Function/Subroutine Documentation
   subroutine dsygs2 (integerITYPE, characterUPLO, integerN, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( ldb,
       * )B, integerLDB, integerINFO)
       DSYGS2 reduces a symmetric definite generalized eigenproblem to standard form, using the factorization results obtained from spotrf
       (unblocked algorithm).

       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**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 DPOTRF.

       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
		     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

		     N is INTEGER
		     The order of the matrices A and B.  N >= 0.

	   A

		     A is 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.

	   LDA

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

	   B

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

	   LDB

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

	   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.

       Date:
	   September 2012

       Definition at line 128 of file dsygs2.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       dsygs2.f(3)