[examples] fix TypeError: 'float' object cannot be interpreted as an index
@@ -150,7 +150,7 @@ bouncingBox.initialize()
# Get the values to be plotted
# ->saved in a matrix dataPlot
-N = (T - t0) / h
+N = int((T - t0) / h)
dataPlot = zeros((N+1, 4))
#
