function material = prepareDensity(global_material, nelx, nely, microx, microy)
    material = cell(nely, nelx);
    for i = 1:nelx
        for j = 1:nely
            material{j,i} = global_material((j-1)*microy+1:j*microy, (i-1)*microx+1:microx*i);
        end
    end
end