How to understand a recursion problem? and how to get its solution value?

Hi guys,

i implemented a quite large code recursively.... the goal is to improve a tour by adding clients until no client is permitted anymore. The abstract pseudocode works like this:

    function [  best_tour ] = improvement( tour )
    if ~isempty(next_client)
        x=next_client(best)                          %client out of a set of clients chosen with a specific criteria
        tour_temp=[tour,x_index_in_tour];            %integration into the tour at a specific index
       if tour fulfills_constraints
             [  best_tour ] = improvement( tour_temp )
              next_client=next_client(next_client~=next_client(best))   %Remove client from set of clients
       else
             %Remove insertion index for this chosen client 
             [  best_tour ] = improvement( tour )                      %Start again improvement and pick next best client from the set of clients
                                                                       %It can even be the same client with another index
       end
   else
   return best_tour
   end

I the code works well which means that a given parameter "tour" is extended to a good solution until no other client can be integrated into this tour without violating constraints. lets call the solution "tour*"

The Problem is that i cannot give the solution back to my main programm!!! i always get back the same solution "tour" that i put in as a parameter although i can see by debugging that there has been created a much better one "tour*"... The strange thing is that when i continue debugging after having got the tour "tour*" then this tour "tour*" is reduced again to the given parameter "tour"...it takes exaclty the same number of steps it took to get from "tour" to "tour*"...so output is the same as the input altough during execution there has been found a much bette rsolution?

i know it has to do with the recursion depth but i dont understand it:( i tried breaking it down to an easy problem like this:

function [ y ] = Improvement_test( x )

y=x
x=x+5;
    if y<42
        y=improvement_test(x)
    end
end

when i execute it with x=20 i get the results: Why is there this 6 times 45 in the end? i just want to have the final solution once and as soon as it is reached i want to break from the rekursion...would be glad to be explained this weird behaviour.

Improvement_test( 20 )

y =

      20

y =

      25

y =

      30

y =

      35

y =

      40

y =

      45

y =

      45

y =

      45

y =

      45

y =

      45

y =

      45

ans =

      45

>>

best regards, John

[Walter Roberson]

Note: MATLAB's return is not to be followed by a value . You cannot say what value is to be returned: the value of the function will be according to whatever was set for the output variables.