In this recipe, we will explain in detail how the Dict and Set types identify keys in Julia.
Creating a function preimage - understanding how dictionaries and sets work
Getting ready
The example that we will use is the creation of a dictionary that stores a preimage function.
Given a function, 
and 
, we will call preimage of 
a set 
; see the example at http://mathworld.wolfram.com/Preimage.html.
In particular, we need to create preimage of all possible values of a mapping, 
, given the domain,
and the set B defined as an image of A under 
, as calculated by Julia.
In the GitHub repository for this recipe, you will find the commands.txt file...
