DATEADD : Used for time intelligence, such as calculating "Year-Over-Year" growth by shifting dates.
SUMX : An "iterator" function that performs a calculation row-by-row before summing the results.
RANKX : Automatically ranks items (like products or sales reps) based on a specific value. Practical PowerPivot & DAX Formulas for Excel 2010
In his book author Art Tennick provides a comprehensive guide for extracting actionable insights from massive corporate datasets. This "hands-on" resource is particularly noted for:
CALCULATE : The most powerful function, used to modify the filter context of a calculation.
: The book includes simplified chapters designed to help users build sophisticated pivot tables in just a few minutes. Essential DAX Formulas for Power Users
: It contains over 250 downloadable DAX formulas that cover everything from basic filtering to complex statistical and time-intelligence functions.
