I have developed Matlab code of an algorithm, but I am unable to run it. Please help me to find error.

3 次查看（过去 30 天）
Amna Habib
Amna Habib 2023-8-4
评论： Voss 2023-8-4
Ran in:
I have developed Matlab code of an algorithm, but I am unable to run it. Please help me to ffix the errors.
Urgent reply will be highly appreciated. Thanks in advnce!
distance_matrix = [0, 29, 20, 21;
29, 0, 15, 18;
20, 15, 0, 30;
21, 18, 30, 0];
tabu_tenure = 5;
max_iterations = 1000;
[best_tour, best_distance] = tabu_search_tsp(distance_matrix, tabu_tenure, max_iterations);
Output argument "best_tour" (and possibly others) not assigned a value in the execution with "solution>perform_tabu_search" function.

Error in solution>tabu_search_tsp (line 36)
[current_tour, current_distance] = perform_tabu_search(current_tour, distance_matrix, tabu_list);
function [best_tour, best_distance] = tabu_search_tsp(distance_matrix, tabu_list_size, max_iterations)
n = size(distance_matrix, 1); % Number of cities
best_tour = randperm(n); % Initialize the best tour with a random permutation
best_distance = calculate_tour_distance(best_tour, distance_matrix);
tabu_list = zeros(tabu_list_size, n); % Initialize the tabu list to store forbidden moves
tabu_tenure = 5; % Tabu tenure (number of iterations for which a move is forbidden)
% Main loop of Tabu Search
for iter = 1:max_iterations
initial_solution = nearest_neighbor_heuristic(distance_matrix);
[current_tour, current_distance] = reversal_heuristic(initial_solution, distance_matrix);
% Check if the current tour is better than the best tour found so far
if current_distance < best_distance
best_tour = current_tour;
best_distance = current_distance;
end
% Add the current tour to the tabu list
tabu_list = update_tabu_list(tabu_list, current_tour, tabu_tenure);
% Perform Tabu Search on the current tour
[current_tour, current_distance] = perform_tabu_search(current_tour, distance_matrix, tabu_list);
% Check if the current tour is better than the best tour found so far
if current_distance < best_distance
best_tour = current_tour;
best_distance = current_distance;
end
% Display the current best distance every 100 iterations (optional)
if mod(iter, 100) == 0
fprintf('Iteration %d, Best Distance: %.2f\n', iter, best_distance);
end
end
end
function distance = calculate_tour_distance(tour, distance_matrix)
n = length(tour);
distance = 0;
for i = 1:n-1
distance = distance + distance_matrix(tour(i), tour(i+1));
end
distance = distance + distance_matrix(tour(n), tour(1)); % Return to the starting city
end
function tour = nearest_neighbor_heuristic(distance_matrix)
n = size(distance_matrix, 1); % Number of cities
tour = zeros(1, n);
unvisited = 1:n;
current_city = randi(n); % Start from a random city
for i = 1:n
tour(i) = current_city;
unvisited(unvisited == current_city) = [];
if isempty(unvisited)
break;
end
[~, next_city] = min(distance_matrix(current_city, unvisited));
current_city = unvisited(next_city);
end
end
function [tour, distance] = reversal_heuristic(tour, distance_matrix)
n = length(tour);
distance = calculate_tour_distance(tour, distance_matrix);
for i = 1:n-1
for j = i+1:n
% Try reversing the segment between city i and city j
new_tour = apply_reverse(tour, i, j);
new_distance = calculate_tour_distance(new_tour, distance_matrix);
% If the new tour is better, update the tour and distance
if new_distance < distance
tour = new_tour;
distance = new_distance;
end
end
end
end
function new_tour = apply_reverse(tour, i, j)
new_tour = [tour(1:i-1), fliplr(tour(i:j)), tour(j+1:end)];
end
function tabu_list = update_tabu_list(tabu_list, tour, tabu_tenure)
tabu_list(2:end, :) = tabu_list(1:end-1, :);
tabu_list(1, :) = tour;
tabu_list(:, tabu_tenure+1:end) = 0;
end
function [best_tour, best_distance] = perform_tabu_search(initial_tour, distance_matrix, tabu_list)
end
  1 个评论
John D'Errico
John D'Errico 2023-8-4
Does your need for an urgent reply make anyone reply more quickly? No. All it does is make somepne like me waste my time, telling you why your question is not in fact urgent. Unless, of course, you are much more important than any of the other people who have asked questions. I am sure they would like a quick response too.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Voss
Voss 2023-8-4
The function perform_tabu_search doesn't do anything.
function [best_tour, best_distance] = perform_tabu_search(initial_tour, distance_matrix, tabu_list)
end
That's the reason for the error you got. Specifically, perform_tabu_search doesn't assign a value to its output arguments best_tour and best_distance.

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Get Started with Optimization Toolbox 的更多信息

标签

产品


版本

R2023a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by