Hi Iomaca,

I think drawdown calculator is probably an overflattering name - it's actually a simulator.
The way it works is thussly:
For every bet of your simulation it creates a random number and lets say your win rate is 20% - if that random number is 0.20001 to 0.99999 you lose, if it's 0.00001 to 0.20000 you win. This gives a pretty realistic representation of your chances of winning any particular race with your preferred system.
It carries this on for all the bets of your simulation and personally I can't think of a better way to emulate the seemingly random chances of your horse winning each race with the claimed strike rate of your system.
When one of these simulated races results in a win for you you get the claimed average winning divvy, your bank after each race is calculated and things like maximum drawdown and longest loosing streak are computed.
When run a number of times it simulates realistically for mine the ups and downs of betting. Sometimes you do better than others and you have no control over whether it's a good run or a bad one.

The only improvement I can see it having is a further random element to vary the dividend it pays out each time you win. This would average out at the claimed average divvy but may be higher or lower with each win.

We'd all like a bit of certainty but this little "toy" mirrors the uncertainty of punting nicely I reckon.

DISCLAIMER. Calculation particulars are in the spirit of the program but may not represent the actual finer points of the mechanics of said program, any losses incurred as a result of using the program are not to be laid at the door of the person writing this disclaimer as he did not program the program.