$ In the "function case" you liquidate the portfolio at $t_1$ realising its PnL (let me simplify the notation a little) Stack Exchange network is made of 183 Q&A communities like Stack Overflow, the most important, most trusted on line Local community for builders to know, share their information, and https://marioptvzc.newbigblog.com/40305117/indicators-on-pnl-you-should-know