/pre><pre>     u = zeros(size(X_));
     u_t = zeros(size(X_));</pre><pre>     A_0 = ry * ones(1, length(y_));
     A_1 = ry * ones(1, length(y_) - 1);
     A = -2 * diag(A_0) + diag(A_1, 1) + diag(A_1, -1);</pre><pre>     B_0 = rx * ones(1, length(x_));
     B_1 = rx * ones(1, length(x_) - 1);
     B = -2 * diag(B_0) + diag(B_1, 1) + diag(B_1, -1);</pre><pre>     for id = 1 : max(slices_id)
         t = id * dt;
         u(:, 1) = reshape(g_0t(y_, t), size(u(:, 1)));
         u(1, :) = reshape(g_0t(x_, t),