bs_tester()

function bs_tester()
  N = [10, 30, 50, 70, 100, 300, 500, 700, 1000];
  D = [0.05, 0.1, 0.15, 0.2, 0.25, 0.3];

  for n = N
    for d = D
      data_count = d * n * n;
      if data_count < n
        display("impossible to create invertible matrix");
        display(n);
        display(d);
        display("");
        continue;
      endif
      A = sprand(n, n, d);
      A = full(A);
      A = triu(A);
      A = A + eye(n); % Make sure matrix is invertible
      [cidx, ridx, data] = full_to_csr(A);
      x = rand(n, 1);
      b = A * x;

      tic();
      x_sparse = sparse_backsub(cidx, ridx, data, b);
      elapsed_time = toc();

      tic();
      x_full = backward_substitution(A, b);
      full_elapsed_time = toc();

      display(norm(x - x_sparse));
      display(n);
      display(d);
      display(elapsed_time);
      display(full_elapsed_time);
      display(full_elapsed_time - elapsed_time);
      display("");
    endfor
  endfor

endfunction