function distance = tnp_dtw2(a_ref, a_test)
% Calcul le chemin optimum selon l'algo de la DTW entre deux tableaux de vecteurs
% [dist] = distdtw(a_test,a_ref)

[long_ref, pole] = size(a_ref);
[long_test, pole] = size(a_test);

dist_local = zeros(long_ref,1);
dist_acc = zeros(long_ref,2);

% Initialisation : Calcul de la 1ère colonne
dist_local(1,1) = sqrt((a_ref(1,:) - a_test(1,:)) * (a_ref(1,:) - a_test(1,:))');
dist_acc(1,2) = dist_local(1,1);
for i=2:long_ref
    dist_acc(i,2) = 1e12;
end

% Calcul pour l'ensemble de la matrice
for k=2:long_test
    % Copie de la colonne de droite dans la colonne de gauche
    dist_acc(:,1) = dist_acc(:,2);
    % Calcul des nouvelles distances uniquement dans la zone autorisée
    a = round(2 * k + long_ref - 2 * long_test);
    b = round(-1 + 2 * k);
    for l = max([a 1]): min([b long_ref])
        dist_local(l,1) = sqrt((a_ref(l,:) - a_test(k,:)) * (a_ref(l,:) - a_test(k,:))');
    end

    % Calcul des distances accumulées uniquement dans la zone autorisée
    if a < 2
        dist_acc(1,2) = dist_local(1,1) + dist_acc(1,1);
    else
        dist_acc(1,2) = 1e12;
    end
    for l = 2:(a-1)
        dist_acc(l,2) = 1e12;
    end
    for l = max([2,a]): min([long_ref,b])
        dist_acc(l,2) = dist_local(l,1) + min([dist_acc(l - 1, 2) dist_acc(l,1) dist_acc(l - 1,1)]);
    end
    for l = (b+1):long_ref
        dist_acc(l,2) = 1e12;
    end
end

distance = dist_acc(long_ref,2);