Calculating parallel periods for multiple dates in a set

In the recipe Calculating the YoY (Year-over-Year) growth (parallel periods), we've shown how the ParallelPeriod() function works and how it can be used to calculate the YoY growth. All we had to do is specify a member, ancestor's level, and an offset, and the parallel member was returned as a result.

OLAP works in discrete space and therefore many functions, ParallelPeriod() included, expect a single member as their argument. On the other hand, relational reports are almost always designed using a date range, with Date1 and Date2 parameters for many relational reports. As the relational reporting has a longer tradition than the multidimensional, people are used to thinking in ranges. They expect many multidimensional reports to follow the same logic. However, operating on a range is neither easy nor efficient. A cube designed with best practices can help, by eliminating the need for ranges and increasing the performance of the cube...