dsygs2(3) [debian 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

Function/Subroutine Documentation
   subroutine dsygs2 (integerITYPE, characterUPLO, integerN, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( ldb,
       * )B, integerLDB, integerINFO)
       DSYGS2

       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:
	   November 2011

       Definition at line 128 of file dsygs2.f.

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

Version 3.4.1							  Sun May 26 2013						       dsygs2.f(3)

Check Out this Related Man Page

DSYGS2(l)								 )								 DSYGS2(l)

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.

       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.

LAPACK version 3.0						   15 June 2000 							 DSYGS2(l)

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