Facility layout objective function in GA Toolbox

I am developing a facility layout using the GA toolbox for 8 departments. My objective function is to minimise the total sum of the product of the facility proximity ratings and the centroidal distances of the facilities. The proximity ratings and centroidal distances are represented by 8x8 matrices. My question is how I can represent the objective function which contains a double summation.

[Walter Roberson]

Is that element-by-element multiplication, or matrix multiplication?

Is the proximity rating table fixed and the centroid distances matrix is the input? Or are (x,y) coordinates for each faculty fixed and a trial (x,y) is what is input, and the objective function will calculate the centroid distances and do the multiplication by the fixed proximity ratings matrix and sum in order to get the "score" ?

[John Kandwe]

Thank you for a quick response.

This is element by element multiplication, the proximity rating table is fixed and the centroid distance matrix is the input, according to the constraints of my mathematical model. I would like the GA to change the inputs in a way that will produce the least possible score which would mean a feasible facility layout.