phew! that was so hard for someone has little understanding of functions let alone sub functions, function handles and nested functions.Those are my tips by the way :) They're saying nested function is way to go but the hardest thing to nail for me was function handle actually!
Also first examples can be deceptive, at first I thought n was not the iteration time and found golden ratio to be sqrt(31) but actually they want you to iterate 1 with the golden ratio function, 30 times.