how to set up the units in vensim

[sally]

hi, i am really confuses about it. how to set up the units in the model,

for example, if the customer demand occurs, i have to compare it with my inventory, but these two variables have the different units, so the system said my units is wrong.

how to figure it out


really need your help

i have attach my file...hope can get some help soon..

[LAUJJL]

Hi

I do not see any unit errors in the model attached.
For your first question, go to the reference manual and look at the second chapter about the Vensim language. It will explain the order taken by Vensim to make calculations.
You should too study the Vensim user's Manual.
Regards.
JJ

[bob@vensim.com]

You can indeed only ship if intentory is positive - but the amount that can be shipped requires a time constant such as the minimum shipping time. Sterman's text "Business Dynamics" has good discussion on issues like this. See also the Molecules.

[sally]

thank you for your reply, i will check the reference manual.

i have another problem, if i want to simulate a situation's time is very short, such as a movie only show for two month , and i want to simulate the situation, how to set up it? i mean how to set up a situation in vensim when it is just show up for short time...

hope you can know my meanings.

hope to get the suggestions soon..

thank you .

[bob@vensim.com]

You can set up a model to run for a short period of time - a few seconds, a few days, a few weeks. If there are some things that happen only during a part of the simulation that is OK, but might mean that you are better off with separate models (eg if you are modeling the decline of the motion picture industry then including the running of any specific movie is probably not useful).