Search found 2590 matches

by tomfid
Thu Apr 04, 2019 3:30 am
Forum: Vensim
Topic: sensitivity analysis (vensim)
Replies: 10
Views: 386

Re: sensitivity analysis (vensim)

Try loading a new Analysis Toolset?
by tomfid
Thu Apr 04, 2019 12:41 am
Forum: Ventity
Topic: Ventity Optimization dialog a bit wonky?
Replies: 4
Views: 363

Re: Ventity Optimization dialog a bit wonky?

I've put in a ticket for this.
by tomfid
Wed Apr 03, 2019 1:09 pm
Forum: Vensim
Topic: Please, help
Replies: 2
Views: 166

Re: Please, help

Also, as a general practice, you should not bury numbers that have dimensions in your equations. Each item (1045, 180) should be made a separate named variable with units.
by tomfid
Tue Apr 02, 2019 11:17 pm
Forum: Vensim
Topic: Crashes frequently on Windows 10
Replies: 11
Views: 367

Re: Crashes frequently on Windows 10

Strange. I can paste with a prefix all day long, no issues.
by tomfid
Tue Apr 02, 2019 10:07 pm
Forum: Vensim
Topic: Please, help
Replies: 1
Views: 140

Re: Please, help

Presumably you have a stock of water in the reservoir, with an inflow (river flow or rainfall or something, presumably exogenous) and an outflow (discharge). I would guess that there's a mechanism something like the following: water in reservoir = INTEG( inflow - discharge, initial water ) inflow = ...
by tomfid
Mon Apr 01, 2019 6:15 pm
Forum: Vensim
Topic: Crashes frequently on Windows 10
Replies: 11
Views: 367

Re: Crashes frequently on Windows 10

Converter = Auxiliary
by tomfid
Mon Mar 25, 2019 5:02 pm
Forum: Vensim
Topic: Giving Excel Data
Replies: 7
Views: 331

Re: Giving Excel Data

Two options: 1. Run the model in days, using the same numbering as Excel dates. (An Excel date is really a number like 34582.) 2. In Excel, create a time row/column that translates dates to a decimal year, week, etc. For example, if cell A2 contains a date, you could translate that to a decimal year...
by tomfid
Thu Mar 21, 2019 11:25 pm
Forum: Vensim
Topic: I plot the chart but the line does not appear
Replies: 9
Views: 340

Re: I plot the chart but the line does not appear

What do you get if you use the table tool?
by tomfid
Wed Mar 20, 2019 9:14 pm
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

Great!
by tomfid
Wed Mar 20, 2019 4:42 pm
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

I think the equation above already does what you want. If you write: c : (c1-c10) y[c] = x[c] + z you assign 10 (presumably different) values of x to 10 values of y. On the other hand, the same single value of z will be used in each computation of y. So, in your case, you just need to be sure that e...
by tomfid
Wed Mar 20, 2019 4:36 pm
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

You can define equivalence relations by defining a new subscript, then changing the variable's subtype to "equivalence" in the equation editor.

See also http://vensim.com/documentation/usr17.htm
by tomfid
Wed Mar 20, 2019 2:42 pm
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

One more thought ... If you do want to use different names for the same dimension, you can use equivalence relations. One common application: City : boston, chicago, denver Origin <-> City Destination <-> City Then you can subscript things with [Origin,Destination] In your case, I'd hope to avoid ha...
by tomfid
Wed Mar 20, 2019 1:20 pm
Forum: Ventity
Topic: Save time step
Replies: 2
Views: 281

Re: Save time step

Actually, I think it's a matter of clarity - those save items pertain only to sensitivity runs. I think the settings are due for a reorg, at which time we could handle regular runs, but that probably won't make 2.0.2, which is imminent.
by tomfid
Wed Mar 20, 2019 1:18 pm
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

2222^13 = 3.2186423e+43 :)
by tomfid
Wed Mar 20, 2019 1:17 pm
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

The fact that these subscripts are all the same size suggests to me that you really just need a single dimension: Catchment : (c1-c2222) or something like that. As is, if you write variable[ManureN,FertN] it will have over 4 million elements, which can be done, but quickly bogs things down. So, I th...
by tomfid
Wed Mar 20, 2019 3:46 am
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

If each subscript range has 2 elements, that's 2^13=8192. 3 elements each would be near the practical limits. I've never seen a model use more than 5 or 6 dimensions.

What's the real-world system under study?
by tomfid
Tue Mar 19, 2019 11:35 pm
Forum: Vensim
Topic: Using fewer subscripts
Replies: 18
Views: 491

Re: Using fewer subscripts

You can have as many subscripts as you want, as long as no single variable uses more than 8.

I think we need more information about your specific problem and model structure in order to give useful advice.
by tomfid
Tue Mar 19, 2019 11:33 pm
Forum: Ventity
Topic: Save time step
Replies: 2
Views: 281

Re: Save time step

Sorry - my subscription to this forum doesn't seem to be working, so I'm just seeing this. Anyway, I can replicate the problem. We'll get it fixed ASAP.
by tomfid
Tue Mar 19, 2019 11:32 pm
Forum: Ventity
Topic: Rabbits by color - help example
Replies: 1
Views: 222

Re: Rabbits by color - help example

When you plot the referenced variable, you're seeing all entities that are active in the Picker. However, if you create a variable in the Farmer that relies on the referenced "white" value, it will use the correct single entity.
by tomfid
Tue Mar 19, 2019 11:06 pm
Forum: Vensim
Topic: Crash Upon Adding New Variable, Possible Memory Issue
Replies: 11
Views: 489

Re: Crash Upon Adding New Variable, Possible Memory Issue

Glad it works.

Is there some alternate structure we could implement that would make it easier to handle the multitude of .cin files?
by tomfid
Tue Mar 19, 2019 7:05 pm
Forum: Vensim
Topic: DLIST2VDF challenges
Replies: 8
Views: 286

Re: DLIST2VDF challenges

I think you'd have to give up the ?file wildcard and use filename.csv directly.
by tomfid
Tue Mar 19, 2019 6:21 pm
Forum: Vensim
Topic: DLIST2VDF challenges
Replies: 8
Views: 286

Re: DLIST2VDF challenges

You can use csv now, if the extension is csv.
by tomfid
Tue Mar 19, 2019 4:54 pm
Forum: Vensim
Topic: DLIST2VDF challenges
Replies: 8
Views: 286

Re: DLIST2VDF challenges

Maybe delimiter guess is a dumb idea and should simply be deleted?
by tomfid
Tue Mar 19, 2019 4:26 pm
Forum: Vensim
Topic: DLIST2VDF challenges
Replies: 8
Views: 286

Re: DLIST2VDF challenges

It turns out to be an easy fix. The algorithm that is supposed to guess the delimiter isn't working for some reason. If you rename the file to .tab, it knows what to do.