利用graphminspantree可以求最小生成树，具体参考MATLAB帮助

% Create an undirected graph with 6 nodes
S=[1 1 2 2 3 4 4 5 5 6 6];%起始节点向量
E=[2 6 3 5 4 1 6 3 4 2 5]; %终止节点向量
W = [.41 .29 .51 .32 .50 .45 .38 .32 .36 .29 .21];%边权值向量
DG = sparse(S,E,W);
view(biograph(DG,[],'ShowArrows','off','ShowWeights','on')) %DG
% Find the minimum spanning tree of DG
[ST,pred] = graphminspantree(DG) %DG
view(biograph(ST,[],'ShowArrows','off','ShowWeights','on'))
V=sum(sum(ST)); % 最小生成树的权
disp(['最小生成树的权为：',num2str(V)]);

%运行结果为

ST =

   (4,1)       0.4500
   (6,2)       0.2900
   (5,3)       0.3200
   (5,4)       0.3600
   (6,5)       0.2100

pred =

     0     6     5     1     4     5

最小生成树的权为：1.63

http://hiphotos.baidu.com/lb%CD%BC%EF%BF%BD%EF%BF%BD%EF%BF%BD%EF%BF%BD/pic/item/12a0b23b083d61a555e72346.jpg

http://hiphotos.baidu.com/lb%CD%BC%EF%BF%BD%EF%BF%BD%EF%BF%BD%EF%BF%BD/pic/item/93afe8e8e6d42c982e2e2146.jpg

                                                                                   最小生成树图