Double Summation For two point correlation

I have to use the double summation function (attached below) where the phi function is the distance formula in three dimensional space. I have the function I need, but I am not sure how to program it into a double summation on MATLAB.

[Alexandra Harkai]

What have you tried so far? What are D and R? What arguments does your phi function take?

Answer 1

[Darshan Ramakant Bhat]

I think the simpler way is to do using two for loops.

   d_sum=0;
   for i=1:length(D)
      x=D(i);
      for j=1:length(R)
         y=R(j);
         d_sum=d_sum+fi_fun(x,y);
      end
    end

Additionally you can try to vectorize the process. Following link may help you

https://www.mathworks.com/matlabcentral/answers/165457-how-to-calculate-double-summation-in-matlb

Regards,

Darshan Bhat