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dporfs.f(3)			    LAPACK			   dporfs.f(3)

NAME
       dporfs.f -

SYNOPSIS
   Functions/Subroutines
       subroutine dporfs (UPLO, N, NRHS, A, LDA, AF, LDAF, B, LDB, X, LDX,
	   FERR, BERR, WORK, IWORK, INFO)
	   DPORFS

Function/Subroutine Documentation
   subroutine dporfs (characterUPLO, integerN, integerNRHS, double precision,
       dimension( lda, * )A, integerLDA, double precision, dimension( ldaf, *
       )AF, integerLDAF, double precision, dimension( ldb, * )B, integerLDB,
       double precision, dimension( ldx, * )X, integerLDX, double precision,
       dimension( * )FERR, double precision, dimension( * )BERR, double
       precision, dimension( * )WORK, integer, dimension( * )IWORK,
       integerINFO)
       DPORFS

       Purpose:

	    DPORFS improves the computed solution to a system of linear
	    equations when the coefficient matrix is symmetric positive definite,
	    and provides error bounds and backward error estimates for the
	    solution.

       Parameters:
	   UPLO

		     UPLO is CHARACTER*1
		     = 'U':  Upper triangle of A is stored;
		     = 'L':  Lower triangle of A is stored.

	   N

		     N is INTEGER
		     The order of the matrix A.	 N >= 0.

	   NRHS

		     NRHS is INTEGER
		     The number of right hand sides, i.e., the number of columns
		     of the matrices B and X.  NRHS >= 0.

	   A

		     A is DOUBLE PRECISION array, dimension (LDA,N)
		     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.

	   LDA

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

	   AF

		     AF is DOUBLE PRECISION array, dimension (LDAF,N)
		     The triangular factor U or L from the Cholesky factorization
		     A = U**T*U or A = L*L**T, as computed by DPOTRF.

	   LDAF

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

	   B

		     B is DOUBLE PRECISION array, dimension (LDB,NRHS)
		     The right hand side matrix B.

	   LDB

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

	   X

		     X is DOUBLE PRECISION array, dimension (LDX,NRHS)
		     On entry, the solution matrix X, as computed by DPOTRS.
		     On exit, the improved solution matrix X.

	   LDX

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

	   FERR

		     FERR is DOUBLE PRECISION array, dimension (NRHS)
		     The estimated forward error bound for each solution vector
		     X(j) (the j-th column of the solution matrix X).
		     If XTRUE is the true solution corresponding to X(j), FERR(j)
		     is an estimated upper bound for the magnitude of the largest
		     element in (X(j) - XTRUE) divided by the magnitude of the
		     largest element in X(j).  The estimate is as reliable as
		     the estimate for RCOND, and is almost always a slight
		     overestimate of the true error.

	   BERR

		     BERR is DOUBLE PRECISION array, dimension (NRHS)
		     The componentwise relative backward error of each solution
		     vector X(j) (i.e., the smallest relative change in
		     any element of A or B that makes X(j) an exact solution).

	   WORK

		     WORK is DOUBLE PRECISION array, dimension (3*N)

	   IWORK

		     IWORK is INTEGER array, dimension (N)

	   INFO

		     INFO is INTEGER
		     = 0:  successful exit
		     < 0:  if INFO = -i, the i-th argument had an illegal value

       Internal Parameters:

	     ITMAX is the maximum number of steps of iterative refinement.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 183 of file dporfs.f.

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

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