this is my equation using matlab , i can't get it manually.

dmat = reshape(sqrt(sum((xy(a,:)-xy(a',:)).^2,2)),N,N);

[njj1]

Your question is really unclear... It's very hard to know what these variables are and their properties without any further details. Moreover, I'm not sure of the exact error you getting, Can you provide more details?

[maatoug ayoub]

its not an error i'm getting this equation from a script of "Fixed Start Open Multiple Traveling Salesmen Problem (M-TSP) Genetic Algorithm (GA)" i just want to get it manually like this : s = sqrt ( (x-10)^2 ---->

[njj1]

So what is your variable 'a'? What is the size of 'xy'?

[maatoug ayoub]

for k = nargin:nargs-1
    switch k
        case 0
            xy = 10*rand(20,2);
        case 1
            N = size(xy,1);
            a = meshgrid(1:N);
            dmat = reshape(sqrt(sum((xy(a,:)-xy(a',:)).^2,2)),N,N);

          case 2
              salesmen = 4;
          case 3
              min_tour = 2;
          case 4
              pop_size = 80;
          case 5
              num_iter = 5e3;
          case 6
              show_prog = 1;
          case 7
              show_res = 1;
          otherwise
      end

[maatoug ayoub]

this is a part of the script

Answer 1

[njj1]

This looks like it's the distance from each (x,y) pair to every other (x,y) pair.

A_{i,j} = \sqrt{(x_i - x_j)^2}, where x = (x,y)

[njj1]

Sorry for the multiple edits. Each entry in the final matrix that I called 'A' (and in the script is called dmat) is the Euclidean distance from one (x,y) pair to another (x,y) pair.

[maatoug ayoub]

thank you very much ..so sum((xy(a,:)-xy(a',:) its equal {(x_i - x_j)

[njj1]

Yes, it is, but they do it in a clever, vectorized way, where they do not have any for loops to cycle through each i,j.

[maatoug ayoub]

thank you my friend now i untrestand it