I am working on a TSP tour construction algorithm, where distances are saved in a distance matrix D, and the tour is represented as a permutation of the n cities.
It starts with a partial tour of two nodes, and from then on it keeps adding an unvisited city until the partial tour contains all cities.
To decide which city to add to the current partial tour, I need a submatrix from the D distance matrix. However, this operation, as it turns out, takes about 90% of full running time. Is there any way to speed this up?
Here is part of my code: (the line that takes most time is the one that defines 'searchArea'
while numel(tour) < n-1 searchArea = D(nodesLeft,tour); %submatrix that needs to be investigated
addCity = findCity(searchArea); %find the city that should be added
addCity = nodesLeft(addCity); %convert 'addCity' from an idx to city number
tour = insertCity(D,tour,addCity); %insert city in partial tour appropriately
nodesLeft = nodesLeft(nodesLeft~=addCity);% update which cities are left over
end
EDIT:
nodesLeft is a shrinking vector containing all numbers not yet in tour.
similarly tour is a growing vector containing all numbers 1:n except for what is in nodesLeft
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