How to compare currentUser with entry.author? How can I compare the results of currentUser and entry.author on an entry page?
I've tried the following, but none of these get a positive result:

{% if  currentUser == 'entry.author.id' %}


Or 

{% set author %}{{ entry.author.id }}{% endset %}
{{ author }}
{% if currentUser.id == '{{ author }}' %}


(I'm aiming to provide a way for the author of an entry to be presented with a form to edit the entry)
Try this:

{% if currentUser.id == entry.author.id %}


When using quotation marks, it means that it's a string in Twig. What you want to do is compare the value of the actual variable.

Also, currentUser is a UserModel, so you need to get the id property to compare it with entry.author.id.