MATLAB: Simulink function’s output is it’s input

Question

Hello. Let's say we have this simple function block that increases it's input by one.

Something like this screenshot: http://i41.tinypic.com/2dj3u47.jpg

It doesn't work, since at the beginning the output is undefined so I need to put some kind of delay. What kind of delay do I put so that output is delayed EXACTLY one step.

Answer 1

Use the "Unit Delay" block from Simulink->Descrete library. Put it in the feedback loop. You can set an initial value for it too. To get the "increment by 1" functionality, the starting number constant needs to be 1.