Fuzzy Davies-Bouldin index for spherical clustering

Input: data set 𝒜 ⊂ (ℝ^n), centers (Subscript[c, 1]),⃛,(Subscript[c, k]) ∈ (ℝ^n), membership matrix U;
Output: FDB index;
Submodules: none needed

Clear[FDB]
FDB[A_,cen_,U_]:=Module[{m=Length[A],k=Length[cen],VV,max,sum=0},
VV=Table[0,{j,k}];
Do[
VV[[j]]=Sum[U[[i,j]]^q Norm[cen[[j]]-A[[i]]]^2,{i,m}]/Sum[U[[i,j]]^q,{i,m}]
   ,{j,k}];
Do[
max={};
Do[
If[i≠j,max=Append[max,(VV[[i]]+VV[[j]])/Norm[cen[[i]]-cen[[j]]] ^2]]
,{i,k}];
sum=sum+Max[max]
,{j,k}];
sum/k
            ]