Any suggestions how to simulated a savings program (like a retirement fund) where one adds monthly contributions which can change in value as one earns more.
Georg - You can do something but is pretty messy and requires post-processing using EXCEL. Start your sim with extra cash on hand, enough to make all future contributions to the port. Then each period that a contribution is to be made adjust CashPct accordingly, decreasing the CashPct as time goes on. Once the sim is finished, you will have to download the results to excel and subtract the excess cash from the equity curve.
For example you might start your sim with $100K in investments and $100K cash. You would have a Buy rule CashPct>50%. There might be a monthly contribution of $1K. After one month you would adjust the cash percentage based on the current value of the portfolio (#Equity) and how much cash is remaining. I’m not going to give you the formula but I can be hired to figure it out 
Steve
Steve, thanks for the advice.
Of course one can do the whole simulation in excel, it is just a tedious exercise.
Sims have a provision for deducting management fees as a percentage of port value. So it should be quite easy for P123 to adjust the algo to allow monthly contributions as well. It should be an easy fix.