Ventana software support forum

Hi Voloschik, You don't have to pay; it's not a hard model to translate, if you give me till the middle of next week since I am busy with some consulting projects, I can do it for you - it would be good practice for me. Just so I have a better overall understanding, could you email me the problem de...

Thank you JJ!

Best. Karan

Just read about it in the manual - it's what I'm looking for! Unfortunately, I haven't bought DSS as yet, but I will in the coming month. Thank you Lee.

Hello! This is based on a problem in Prof Coyle's book (Practical Approach to SD, Chapter 10, Freezing of forecasts). Lets say I take a sample ("samfcast") of a product demand forecast "fcast" in March every year, this sample is held for 3 months, till June, for accounting purpos...

JJ - Merci beacoup, vous êtes très gentil!

One possible solution since I cannot use SMOOTH, could be that I use SMOOTHI and give an initial value to the "average recruitment rate".

Greetings! I seem to be having more problems.... Attached is a management consultancy problem (Coyle, Practical Approach to SD, P.157) 1. I get simultaneous equations (problem areas marked in red) if I use the initial state / level values given in the problem. 2. I also get simultaneous equations if...

The appendix of Industrial Dynamics does in fact give the formula for calculating phase and gain from input period and delay period across system components; however, it doesn't explain the necessity for making the system open loop, nor does it explain why feedback structures have to represented as ...

JJ - much appreciated!

Hi JJ, Thank you.... I have, in fact, worked out the DMC problem in Vensim and am not looking for a solution; however, I am curious, about seeing if my results match up with your output and how our practical modeling techniques differ - I think this is a good way to learn from a seasoned SD'r as you...

In Michael R. Goodman's book "Study Notes in System Dynamics", a fair amount of attention is paid to understanding input/output gain and phase relationships of closed loop systems. One interesting method to understanding these relationships is to: 1) initialize the system in steady state; ...

Hi JJ,

I was just taking you up on your offer to share the other models you might have built for the DMC problem in Coyle's book.

Best.

Karan

[Edited on 5-20-2009 by karankhosla]

Dear JJ,

Thank you! If you have a few moments, could you please email me what you think might be useful (to use as a reference, of course!):

karankhosla@gmail.com

By the way, good advice on the book!

Best

Karan

Dear Wilson Wilson, indeed it does work! However, I don't quite understand why I have to use DRMS as the initial value for RMS instead of (PR production rate-APR average production rate)*TARMS+WAP raw material stock coverage*APR average production rate Shouldn't equilibrium initializations work the ...

Dear Jean-Jacques, if you are online, this question is for you! Why does the author create a rate (PR.KL) which is dependent on it's own average (APR.K) thus creating set of simultaneous equations? This requirement is of the policy control part of the DMC model (Page 217 of R.G Coyle's book "SD...

For a time varying Sinusoidal:

Aux = A*SIN(2*Pi*Time/P) {Units}

Set up the auxiliary variable "Aux", input 3 constants A (Amplitude), P (Period), Pi (3.142). Then introduce a ghost variable of time. Finally create information links from these parameters to the "Aux" variable.

If I buy Vensim DSS for Windows XP in the next week or so, will I get a free upgrade to Mac OSX (for the same build version of course), if and when it comes out?

Bob,

Are there plans to release a Mac OS X native version of the Vensim family?

Best.

Thanks Tony, that is good advice! I didn't think of that.

One has to pay extra close attention to units in Vensim. If you run a units check for the following type of formula (taken from a Stella model in which the demand curve for a product is pre-defined) Price {Dollars/Units} = 10 - 0.0078*Q - will yield a units error in Vensim, but not in Stella. I set ...

Greetings! Could someone please help me understand why Vensim gives me an error for units of measure when I want to use equations such as the following: Price = 10-0.00794*Q Units of Measure that I would like in the model: Q = {Units}, Price = {$/Month} Vensim will not give me a clear on the Units C...

I have been working through the six books published by Springer Publications "Modelling Dynamic Economic/Biological/Business etc Systems". There are hundreds of examples in iThink format; over the past six months I have been converting each model into Vensim. After reading Professor Sterma...

Greetings! I am having trouble creating nested/multiple conditional statements in Vensim PLE Plus (there are no options for AND or OR) I would like to create a variable for a signal that jumps to a selected value once the rate of change crosses zero (less than or equal to) and time is greater than 1...

Thank you very much Bob! However, I believe that the QUEUE functions are not available to PLE users; Do you perhaps have a coflow structure suggestion/solution for me?

Greetings! In the simple discrete model (attached) of a queue, I would like to find the average cycle time it takes for a customer to get service (problem taken from Chapter 4, Modeling Dynamic Economic Systems by Bruce Hannon). In Stella, this is done simply by creating using a built in function th...