Unit Tests for Position/Portfolio - While I've not mentioned it directly in diary entries #1 and #2, I've actually been writing some unit tests for the Portfolio and Position objects. Since these are so crucial to the calculations of the strategy, one must be extremely confident that they perform as expected. An additional benefit of such tests is that they allow the underlying calculation to be modified, such that if all tests still pass, we can be confident that the overall system will continue to behave as expected.
We also apply a concentrated margining requirement to Margin accounts. An account's two largest positions and their underlying derivatives will be re-valued using the worst case scenario within a +/- 30% scanning range. The remaining positions will be re-valued based upon a move of +/-5%. If the concentrated margining requirement exceeds that of the standard rules based margin required, then the newly calculated concentrated margin requirement will be applied to the account.
I post this to let you know, as the title mentions it, that I made a trading diary, with google documents tool. This a generic spreadsheet which allows any trader to manage his trading (his risk, his pnl, his opened position, the orders...) with a trding diary. Every trader,should have one, and I mad mine with google docs. At least you must have an account to acces this spreadsheet.