Creating a Cobweb Diagram in MATLAB

[AnitaBillie]

I am trying to create a cobweb diagram in matlab. However, I am not sure what I am doing wrong. When I enter the function in with its initial value and r value...my diagram comes up with 2 straight lines and not a cobweb. I am stuck.

Attached are the m.files

 

[Pythagorean]

I think people will be more willing to help you if you just post the text from both of the program