Ok, it’s a long title, but it’s the best I came up with.
So here’s the story. At work there was a sales report with a nice matrix. On the rows, we had several product attributes like category, subcategory and so on. On the columns it was a bit weird because they wanted to show the day of sale, but also compare with the day of sale from the previous year, and with some particular logic for comparison: if current year had equal or more days of sale than the previous one, it should match day one with day one and so on. However, if previous year had more days of sale, it should match starting from the back, so day one of sale would be matched with day 2 or 3 of previous year. Anyway, this is just to say that I put a measure saying what was the actual day of sale for current year, and previous year, as well as the actual date, because sales are different depending on the day of the week. Then we had cumulative sales, daily sales, for current and previous year. So far so good. Oh I forgot. On top of that there was like % over forecast measure that was the source of all ills.