Use of RANKX with decimal numbers in DAX #powerpivot #ssas #tabular

Using decimal numbers in Power Pivot and Tabular might produce small rounding differences in certain calculations. This is nothing new when you work with floating point, as many programmer knows. The implementation of RANKX might suffer of a behavior producing wrong results when the measures used for the ranking returns a decimal value. For example, consider the following model, where there are three names (A, B, C), each one with a value resulting from the sum of rows in the fact table and a Pos measure, calculated using the following measure: