$ Inside the "function circumstance" you liquidate the portfolio at $t_1$ realising its PnL (allow me to simplify the notation somewhat) Depreciation = worth at the beginning of the calendar year (opening equilibrium) + buys within the year − benefit at the end of the year (closing equilibrium) Comparing P&L https://jeffreyixdwb.affiliatblogger.com/86137839/details-fiction-and-pnl