Random Number Generator with Decreasing Range

This is what I had:

 for x=1:20
    GraphMain=mexGraphNodeRemove(GraphMain,randi([0,21-x]))
 end

I just want to remove a random node within an increasingly narrow range. I don't get an error message with this, but none of my nodes get deleted.

[Guillaume]

The problem is most likely with mexGraphNodeRemove which looks like a mex file you've written. I don't see how we can help.

Note: I would assume that whatever GraphMain is, it has a property for the number of nodes, so rather than using a for loop, I would have used a while loop:

while GraphMain.NodeCount > 0 %or whatever way you have to get the number of nodes
   GraphMain = mexGraphNodeRemove(GraphMain, randi([0 Graphmain.NodeCount]));
end