Entering a new imit order with order lifetime (day) into the trading software of your bank.

Calculation of PnL statement (Profit and Loss of a trading position)

Calculating the portfolio risk in a hedge fund.

Calculation of Net Asset Value (NAV) in a mutual fund. 

Changing the Limit of your order using the trading software of your bank.

Running a backtesting to check the profitability of your new algo.