Iteration to find solution to a piece-wise function

I know that x0 = -3 and need to calculate x10. I have attempted to use a for loop with if and else if commands but it doesn't seem to be working. What code should I enter in MATLAB to produce the desired result?

[Walter Roberson]

duplicates http://uk.mathworks.com/matlabcentral/answers/233569-calculating-values-from-an-iterative-map