This is the simplest rank function, equivalent to the concept of "row numbers".
Also known as Row Number, Unique Rank, Simple Rank
Inputs and Setup:
Partitioning and Addressing:
There are no ties - rank goes in the order listed, with tied items ordered by their sorting. Values of 5, 3, 3, 2 would produce ranks 1, 2, 3, 4.
Adopted from James Baker: http://community.tableau.com/thread/108966