#include <stdio.h>

#include <gsl/gsl_linalg.h>

int

main (void)

{

  double a_data[] = { 0.18, 0.60, 0.57, 0.96,

                      0.41, 0.24, 0.99, 0.58,

                      0.14, 0.30, 0.97, 0.66,

                      0.51, 0.13, 0.19, 0.85 };

  double b_data[] = { 1.0, 2.0, 3.0, 4.0 };

  gsl_matrix_view m 

    = gsl_matrix_view_array (a_data, 4, 4);

  gsl_vector_view b

    = gsl_vector_view_array (b_data, 4);

  gsl_vector *x = gsl_vector_alloc (4);

  int s;

  gsl_permutation * p = gsl_permutation_alloc (4);

  gsl_linalg_LU_decomp (&m.matrix, p, &s);

  gsl_linalg_LU_solve (&m.matrix, p, &b.vector, x);

  printf ("x = \n");

  gsl_vector_fprintf (stdout, x, "%g");

  gsl_permutation_free (p);

  gsl_vector_free (x);

  return 0;

}