Sum of squared errors(how to calculate)

[sailu.garapathi]

I am wondering how shud we calculate SSE(which is automatically computed in weka) by hand.

Suppose for eg :
We have the clusters 1,2,3 below
1. (A1, B1, C2)
2. (A3, B2, B3)
3. (A2, C1)
and the centroid for 1,2,3 clusters are listed below respectively.
1. (3.67,9)W1
2. (7,4.33)W2
3. (1.5,3.5)W3

How do we calculate SSE?
is it Dist(A1,W1)2 + Dist(B1,W1)2 + Dist(C2,W1)2 + Dist(A3,W2)2 + Dist(B2,W2)2 + Dist(B3,W2)2+ Dist(A2,W3)2 +
Dist(C1,W3)2

[Henryrugal]

You are set a brain twining sum. I want to do try..