Water Rocket Simulator

[christheman200]

I've created my own water rocket simulator, which calculates the total acceleration that a rocket can achieve. It is based in Matlab.
Its results are quite similar to those of other simulators found online.

I need some of you to check over my calculations, to make sure that they are correct, and that I am not using incorrect formulas. I am new to mathematical physics, so please bear with me.
Attached is the Matlab file, however I will show my formulas here:

ChangeInWaterVolume = ExhaustVelocity * NozzleArea * TimeStep
WaterRemaining = WaterRemaining - ChangeInWaterVolume

This is the formula I am the most concerned about, as I have seen other formulae to calculate pressure.
CurrentPressure = PressureInitial * ((BottleVolume - InitialWaterVolume)/(BottleVolume - WaterRemaining))^Gamma

I am roughly sure that this equation is correct.
ExhaustVelocity = sqrt (2*(CurrentPressure - AtmosphericPressure) / DensityWater)

Thrust = ExhaustVelocity/9.8*(ChangeInWaterVolume/TimeStep)*DensityWater*9.8

Acceleration = (Thrust/(WaterRemaining*1000 + DryMass))

NewVelocity = OldVelocity + Acceleration*TimeStep

[christheman200]

Here is a link to a text version of the Matlab file, which you can read, or copy and paste into Matlab.
Edit: http://textuploader.com/kzjn