Many thanks for your help.
Scaling issue
Scaling issue
I am using Vensim PLE Plus for Windows (xp) version 5.4 d with a very simple model where I repeatedly input 30 mg of a substance in a "body". I made no scale change. At the first iteration, where I should have 30 mg in the body, I only get 0.3 on the y axis of the resulting graph. I looked in this forum, I checked my model a number of times, redrew it completely and get the same result. Can anybody help me with this? It (I) appear(s) so stupid!
Many thanks for your help.
Many thanks for your help.
Scaling problem
Hi
Can you just send your model or a model simplified. Il will be easier to spot the problem.
Regards.
J.J. Laublé
Can you just send your model or a model simplified. Il will be easier to spot the problem.
Regards.
J.J. Laublé
-
bob@vensim.com
- Senior Member
- Posts: 1107
- Joined: Wed Mar 12, 2003 2:46 pm
At a guess you are assuming difference equations, but have set TIME STEP to a number less than 1. If you want to do difference equations set time step to 1 - but it is better to conceptualize as a differential equation in which case rates are derivatives of the levels - so a rate of 30 mg/second causes the level to incrase with a slope of 30 mg/second.
If you put in units and do units checking things may become clearer.
If you put in units and do units checking things may become clearer.