Practical Powerpivot & Dax Formulas For Excel -

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 Practical PowerPivot & DAX Formulas for Excel

CALCULATE : The most powerful function, used to modify the filter context of a calculation. SUMX : An "iterator" function that performs a