Handling Divide by null in Cubes for PPS, a better way than IIF()

Today i needed to get rid of the “1.#INF” error you get from SSAS when there is a divide by zero or null. The reason for this was that i was building a scorecard in PPS that had a “% change from previous month” calculated member as one metric in the KPI. This was specified as (Current-Previous)/Previous with the appropriate format string. When there was no activity in the previous month Previous would be null and this would give the error. I wanted to produce null instead so i could use the PPS scorecard option to replace null with a custom string.. in my case just a hyphen (i.e. “-”)