data model - pivot calculations

Hi In the pivot i have two coulmn with number values I would like to create third column with ratio of those two compute coulmn. Is it possible?. I do not want to add to the search in the data model because then other attributes I can not use. e.g Column1/column2=column3 Data Column1 Column2 Column3 01-01-2015 100 200 0.5 02-02- 2015 200 100 2