Position Sizing

["Jody Ellis" <ellis_jody@xxxxxxxxxxx>]

I am trying to play around with an martingale type position sizing formula 
that adds another contract with each winning trade. Below is the code I have 
used and have tried many variations, but I cannot seem to get it to work.

The idea is once I have a loss, the num variable returns to 1 and starts 
again. So, if I have a win, then num goes to 2 for the next trade. If I have 
2 winners, num goes to 3 etc,etc. I want the system to increase with a new 
contract with each consecutive win.

I have read many times that Anti-Martingale strategies work best, but I just 
want to see the differences for myself. I have tried this on an S&P system 
and after the first winner of 1 contract the system then buys amounts like 
11, 76, 27 etc on the next trade. Can somebody help me out? Here's the code:

Variables: Num(1);

If PositionProfit(1) < 0 Then Num = 1;
If PositionProfit(1) > 0 Then Num = Num + 1;

Buy Num Contracts Blah Blah;

I have also tried this code but it still won’t count correctly:

Variables: Num(1);

If PositionProfit < 0 Then Num = 1;
If PositionProfit >= 0 Then Num = Num + 1;

Buy Num Contracts Blah Blah;

I have also tried setting the PositionProfit up as a variable and referring 
to it, but still no joy. Here’s that attempt:

Variables: Num(1), PP(0);

PP = PositionProfit;

If PP < 0 Then Num = 1;
If PP >= 0 Then Num = Num + 1;

Buy Num Contracts Blah Blah;

Any ideas? Thanks.