[Help-gsl] Advise on how to refine LU decomposition

[Olumide]

Hello,

I'm trying to use the function gsl_linalg_LU_refine() refine the 
solution of a linear system that was computed by gsl_linalg_LU_decomp 
and gsl_linalg_LU_solve, but I'm getting very unusual results. I'd 
appreciate help debugging the following bit of code, or perhaps a short 
snippet illustrating proper use of gsl_linalg_LU_decomp.

Thanks,

- Olumide


gsl_vector* DenseMatrixSolver::gsl( double *rbfMatrixData , double 
*constrainValdata , unsigned matrixDim )
{
	gsl_matrix_view copy_rbfMatrixView = gsl_matrix_view_array( 
rbfMatrixData, matrixDim , matrixDim );
	gsl_vector_view copy_weightVecView = gsl_vector_view_array( 
constrainValdata , matrixDim );		

	gsl_matrix_view rbfMatrixView = gsl_matrix_view_array( rbfMatrixData, 
matrixDim , matrixDim );
	gsl_vector_view weightVecView = gsl_vector_view_array( constrainValdata 
, matrixDim );		

        /////////// solve (by LU decomposition) ///////////

        int s;
        gsl_vector *weight = gsl_vector_alloc( matrixDim );
        gsl_permutation *perm = gsl_permutation_alloc( matrixDim );

        gsl_linalg_LU_decomp( &rbfMatrixView.matrix , perm , &s );
	gsl_linalg_LU_solve( &rbfMatrixView.matrix , perm , 
&weightVecView.vector, weight );

        /////////// refine LU decomposition ///////////

        gsl_vector *res = gsl_vector_alloc( matrixDim );
	gsl_linalg_LU_refine( &copy_rbfMatrixView.matrix , 
&rbfMatrixView.matrix , perm , &copy_weightVecView.vector , weight , res );
        return weight;
}