In most jurisdictions you can't really patent the use of an abstract mathematical formula on a computer with no gain, but that's something the law has only caug

In most jurisdictions you can't really patent the use of an abstract mathematical formula on a computer with no gain, but that's something the law has only caught up to in the last decade. The patent is most likely invalid in the EU and US but was approved way back when those standards for invalidity didn't exist in their current forms. Of course, a court wouldn't need to be bound by the original decision of the examiner and would determine validity based on current case law and practice.