Running Total by Category & Date

[adeel_nazir]

How can i calculate running total by category sorted by Date.
I know there is option available by using running_total(Amount) from calculation but i need to show by each category and date. Amount should be reset by change of category.

cat | amount | Date | RunningTotal
1 | 10 | Day1 | 10
1 | 10 | Day2 | 20
1 | 10 | Day3 | 30
2 | 10 | Day1 | 10
2 | 10 | Day2 | 20
2 | 10 | Day3 | 30
2 | 10 | Day4 | 40
3 | 10 | Day1 | 10