Search found 3806 matches
- Tue Feb 02, 2016 4:47 pm
- Forum: Vensim
- Topic: DelayN with leakage?
- Replies: 6
- Views: 3743
Re: DelayN with leakage?
It seems like a funny dataset - I wouldn't think people would have accurate perceptions of lifetimes for durable equipment. Plus, as you point out, their confidence bounds may be uncalibrated. Anyhow, I wouldn't think that a variable delay order between levels was desirable. Even if the leakage prob...
- Mon Feb 01, 2016 7:18 pm
- Forum: Vensim
- Topic: DelayN with leakage?
- Replies: 6
- Views: 3743
Re: DelayN with leakage?
It seems like an array would be a reasonable solution, as long as your model isn't too big overall. For example, you could have a fixed-length array (say 100 levels) and vary the delay per level. That would allow you to vary the de facto delay order over any given horizon. Then, once calibrated, you...
- Mon Feb 01, 2016 7:14 pm
- Forum: Vensim
- Topic: Binomial option pricing using Vensim
- Replies: 9
- Views: 5165
Re: Binomial option pricing using Vensim
It's very close to the Brownian motion example model I linked, and also to the Polya urn: http://models.metasd.com/polya-urn-with-increasing-returns/ I think this is what you're after: Binomial.mdl The tree isn't explicitly represented in the model (though you could probably do that with an array). ...
- Mon Feb 01, 2016 7:00 pm
- Forum: Ventity
- Topic: Email problem
- Replies: 1
- Views: 2862
Re: Email problem
info@ventity.biz is the preferred address, but I've just enabled that one too.
- Mon Feb 01, 2016 6:55 pm
- Forum: Vensim
- Topic: Auto regenerated hidden variables
- Replies: 4
- Views: 2531
Re: Auto regenerated hidden variables
You can promote a shadow variable to a regular variable with the "Model Variable" tool in Pro/DSS. That tool doesn't exist in PLE, because each variable has a regular instance that can't be converted to a shadow. However, it may be that there's some way to delete the primary instance in PL...
- Fri Jan 29, 2016 3:40 am
- Forum: Vensim
- Topic: Data loss in SFD: how to trace?
- Replies: 11
- Views: 6960
Re: Data loss in SFD: how to trace?
I can open it and run it. It looks like templat.pdf but not diagram.pdf (presumably that is something else?). However, the structure is nonstandard. If I drag the shadow variables that appear below the stock elsewhere, I can see that they're connected with information arrows, rather than rates. Also...
- Fri Jan 29, 2016 3:30 am
- Forum: Vensim
- Topic: Binomial option pricing using Vensim
- Replies: 9
- Views: 5165
Re: Binomial option pricing using Vensim
I can't remember if Binomial is in here, but this contains some stochastic processes:
http://models.metasd.com/stochastic-processes/
It can definitely be done. Also see
https://www.vensim.com/documentation/in ... zation.htm
which may be of use.
http://models.metasd.com/stochastic-processes/
It can definitely be done. Also see
https://www.vensim.com/documentation/in ... zation.htm
which may be of use.
- Thu Jan 28, 2016 2:35 pm
- Forum: Vensim
- Topic: DelayN with leakage?
- Replies: 6
- Views: 3743
Re: DelayN with leakage?
Sorry - haste makes for dumb answers. I can't see a way to do it without using arrays. What's the time horizon and mean time to failure? What makes the order so high? I wouldn't expect equipment to fail that way. Or is it a mix of failures and rules, such that things are replaced when they fail (low...
- Wed Jan 27, 2016 12:44 am
- Forum: Vensim
- Topic: Data loss in SFD: how to trace?
- Replies: 11
- Views: 6960
Re: Data loss in SFD: how to trace?
Can you post the model and describe what disappeared?
This is not normal or common.
This is not normal or common.
- Tue Jan 26, 2016 7:31 pm
- Forum: Vensim
- Topic: DelayN with leakage?
- Replies: 6
- Views: 3743
Re: DelayN with leakage?
Would DELAY CONVEYOR work? That has leakage. https://www.vensim.com/documentation/in ... nveyor.htm
- Mon Jan 25, 2016 8:18 pm
- Forum: Vensim
- Topic: Workforce modelling
- Replies: 8
- Views: 3934
Re: Workforce modelling
We're not just being pedantic here, by the way - getting the units right is a big aid to the reader. They make it easier to interpret variables. In my experience, fixing all the units errors in a model will identify at least a third of the bugs.
- Mon Jan 25, 2016 8:09 pm
- Forum: Vensim
- Topic: modeling cyclical demand pattern into a constant variable
- Replies: 6
- Views: 3354
Re: modeling cyclical demand pattern into a constant variabl
You don't necessarily need to repeat the data four times in your lookup. You could do something like the following: demand = demand lookup( month index ) ~ widgets/month month index = MODULO( time, twelve months ) ~ dmnl twelve months == 12 ~ months The month index will then be a repeating index wit...
- Wed Jan 20, 2016 8:28 pm
- Forum: Vensim
- Topic: How to force a value in a level variable?
- Replies: 6
- Views: 6089
Re: How to force a value in a level variable?
This is dimensionally inconsistent, because Level has units of stuff, and Rate has units of stuff/time.
The unit error is a hint that you are implicitly assuming TIME STEP = 1, which is not a good idea in general.
The unit error is a hint that you are implicitly assuming TIME STEP = 1, which is not a good idea in general.
- Mon Dec 14, 2015 2:39 pm
- Forum: Vensim
- Topic: How to force a value in a level variable?
- Replies: 6
- Views: 6089
Re: How to force a value in a level variable?
I tend to use something like the following: Indicated outflow = ... (something that could be too big) Actual outflow = MIN( Indicated outflow, Max outflow ) Max outflow = stock/min time to empty Min time to empty = ... (TIME STEP or greater) If there are multiple outflows, you can do something like:...
- Sun Dec 13, 2015 4:21 am
- Forum: Vensim
- Topic: PLE can't import data from xls?
- Replies: 4
- Views: 2956
Re: PLE can't import data from xls?
This is a job for Pro or DSS.
- Mon Dec 07, 2015 4:41 pm
- Forum: Vensim
- Topic: How to use "GET XLS LOOKUPS" and "LOOKUP EXTRAPOLATE" togeth
- Replies: 6
- Views: 3070
Re: How to use "GET XLS LOOKUPS" and "LOOKUP EXTRAPOLATE" to
Messages about an input exceeding the range of a lookup are just warnings, so that's probably not the problem. The origin of the floating point error is most likely something in the other dynamics of your model. One possible test would be to make the lookups flat (i.e. same output value for all inpu...
- Sun Dec 06, 2015 5:48 am
- Forum: Vensim
- Topic: Combining variables with subscripts into a new variable
- Replies: 3
- Views: 2811
Re: Combining variables with subscripts into a new variable
If you map (sub1-sub5) to (a1-a5), (a6-a10) and (a11-a15), you should be able to do it in three equations. I'll have to scratch my head a bit to work out the details.
- Mon Nov 30, 2015 3:34 pm
- Forum: Vensim
- Topic: building control panel (need help)
- Replies: 10
- Views: 4575
Re: building control panel (need help)
You could do something like: Data 1 = GET XLS ... Data 2 = GET XLS ... etc. Scenario = IF THEN ELSE( switch = 1, data 1, IF THEN ELSE( switch = 2, data 2, ... Make "switch" a constant with range 1 to 4 and interval 1, so you can easily select the source in synthesim. This can be done more ...
- Wed Nov 25, 2015 4:21 pm
- Forum: Ventity
- Topic: cohort modeling examples
- Replies: 21
- Views: 15497
Re: cohort modeling examples
We haven't implemented discrete delays and the like yet, mainly because there hasn't been a request. My experience with conveyors with leakage and similar builtin functions is that I can never use them, because there's always some minor violation of the assumptions of the structure. So, I can think ...
- Mon Nov 23, 2015 6:00 pm
- Forum: Vensim
- Topic: Run a model but simultaneous equations involving
- Replies: 7
- Views: 5494
- Mon Nov 23, 2015 3:30 am
- Forum: Vensim
- Topic: Sensitivity Analysis
- Replies: 1
- Views: 1524
Re: Sensitivity Analysis
That's a PLE Plus (or higher) feature.
It wouldn't take too long to run a set of sims in synthesim, if you don't need a large sample.
It wouldn't take too long to run a set of sims in synthesim, if you don't need a large sample.
- Sat Nov 21, 2015 1:52 am
- Forum: Vensim
- Topic: Run a model but simultaneous equations involving
- Replies: 7
- Views: 5494
Re: Run a model but simultaneous equations involving
You have the Type for your stocks set to Auxiliary.
If, for example, you change the type of Population to Level, and enter an initial value, that eliminates the simultaneity. I think the other errors are similar.
If, for example, you change the type of Population to Level, and enter an initial value, that eliminates the simultaneity. I think the other errors are similar.
- Thu Nov 19, 2015 1:43 am
- Forum: Vensim
- Topic: Repeat time period with FINAL TIME as INITIAL CONDITION
- Replies: 1
- Views: 1455
Re: Repeat time period with FINAL TIME as INITIAL CONDITION
You can use the Based On simulation setting to reset the state variables - see https://www.vensim.com/documentation/23320.htm. This is SIMULATE>BASED in a command script. Not sure about iterating n times - you might do that with a command script, or using a programming language with the .dll.
- Wed Nov 18, 2015 1:33 am
- Forum: Vensim
- Topic: Sensitivity Graph is not displayed
- Replies: 1
- Views: 1554
Re: Sensitivity Graph is not displayed
This may be due to screen resolution that's not sufficient to show everything. You can modify your toolset with Tools>Analysis Toolset>Modify, or shrink the icons with Tools>Options>Toolbars.
- Mon Nov 16, 2015 6:49 pm
- Forum: Vensim
- Topic: How to model the different components of a mixture
- Replies: 6
- Views: 3685
Re: How to model the different components of a mixture
What exactly are you doing when this happens? Can you post a screenshot?
I have no trouble adding dimensions to your example.
I have no trouble adding dimensions to your example.