Vensim2Java - Penicillin model

This model shows the growth of a bacterium over time in order to demonstrate the effect of periodic doses of penicillin. The slider bar featured in the applet allows the initial amount of bacteria to be changed without having to resubmit the original Vensim equations.

The dosage times are calculated using several of Vensim's built in functions.

IF THEN ELSE(<condition>, <result 1>, <result 2>):
If <condition> is true the function's value is <result 1>; if it is false, the value is <result 2> instead.

MODULO(<x>, <base>):

Returns the remainder of <x> divided by <base>.

PULSE(<start>, <duration>):

This is a boolean function, which means it can only return 2 values: true (1) or false (0). The pulse function returns 1 over the interval [<start>, <start>+<duration>].

Note: Vensim's pulse function is not the same as Stella's pulse function.

It should be noted that these are especially susceptible to error when advanced integration schemes and adaptive time steps are used. Tweak the default settings (Euler integration without adaptive time steps) and compare the results.

penicillin model:
Vensim penicillin model

Click here to download the equations as text