I have developed Matlab code of an algorithm, but I am unable to run it. Please help me to find error.
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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);
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 Commento
John D'Errico
il 4 Ago 2023
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.
Risposta accettata
Voss
il 4 Ago 2023
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.
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