Ventana software support forum

Maybe the STEP function is what you're looking for. Please take a look at my model.

Have a nice day,
BP

If you don't want a stock to go negative, a good method is to use first-order negative feedback control. However, it is sometime difficult to formulate a correct equation for this. You can also use the MIN function. For instance, "deaths" for pest population could be formulated as MIN(para...

Yes, I am using Apple applications. I have tried paintbrush (http://paintbrush.sourceforge.net) and Autodesk Sketchbook from the app store.

Are Apple applications not capable of producing valid bmp files for Vensim?

I can use your image. That means I must be doing something wrong when creating my .bmp file.

Thank you. I will try a different tool to create my bmp file and see if that helps.

How can I verify if my image is valid? It has the .bmp extension.

Could you share your image with me so that I can try it on my machine? At least we'll know if that's the problem.

Dear Vensim gurus, I am using VensimDSS on a macbook pro retina (Yosemite 10.10.1). I am trying to replace the cloud icons with my own generated bmp image. To do so, I right-click a cloud and then use the "import" option. Then, I choose my file and click "ok". At that moment, Ven...

The previous post is correct, deaths = adults / longivity To make sure you keep the "adults" stock positive, use the following equation (it takes everything from the stock, or what it needs). deaths = min ( adults / time step , adults / longivity ) You should also add units to your model....

If longevity is known, why don't you formulate deaths as adults/longevity?

Hi, If I understand what you're trying to do, I guess you could have two stock and flow structures : one to keep track of the debt to be paid, and the other one to keep track of the investment money. The two would then be connected because part of the investment money would serve to repay the debt. ...

It would be great if Vensim had better scaling for retina displays. I run Vensim on a macbook pro retina, and everything looks blurry.

Using a tool like "Retinizer" helps a little, but much of the interface still looks wrong.

Thank you!

Hi, There are some issues with your model. a) Variable types « Hunger » should be an auxiliary variable, not a stock. Stocks can only change through their flows. Stocks may only affect auxiliary or flow variables. b) Variable names « Food eaten » could be named « eating », and « metabolism » could b...

Hi, On the hardware side of things, I would take a look at CPU and RAM. Is your CPU reaching 100% while you're doing simulations, or is something else the bottleneck? What exactly is your CPU? Is your RAM full? How much do you have installed? Also, do you have Windows XP 32 bits or 64 bits? With tha...

Many thanks to you both!

Indeed, the model now behaves exactly how I thought it should. I realize subcripts require extra attention!

Have a good day,
BP

Hi, Could someone please take a look at my model and explain to me the ouflow behavior? I was expecting to see CV to ouflow between time=0 and time=10 at a rate of 1. That is what happened. At time=10, I also thought the other components would start to outflow. But what I am observing is that all th...