Search found 3804 matches

by tomfid
Thu Jul 21, 2016 3:31 am
Forum: Vensim
Topic: Optimization of time dependent variable (non-constant) for electricity generation expansion planning
Replies: 11
Views: 8322

Re: Optimization of time dependent variable (non-constant) for electricity generation expansion planning

My initial reaction is that this seems like a good approach. Unfortunately I'm teaching today and traveling tomorrow, so I probably won't be able to comment in depth immediately. One general recommendation for situations like this is to be sure to use the random multistart option, to prevent the opt...
by tomfid
Wed Jul 20, 2016 12:22 pm
Forum: Vensim
Topic: Optimization of time dependent variable (non-constant) for electricity generation expansion planning
Replies: 11
Views: 8322

Re: Optimization of time dependent variable (non-constant) for electricity generation expansion planning

Have you explored the second suggestion in the other thread, using VECTOR LOOKUP? That seems like it would address your need. You'd be estimating something like NewCapacity[source,timeslice], with VECTOR LOOKUP picking a value at each timeslice for each source. You'd have a combinatorial explosion p...
by tomfid
Thu Jul 14, 2016 10:36 pm
Forum: Vensim
Topic: Variable depending on time +delay
Replies: 2
Views: 1513

Re: Variable depending on time +delay

I know exactly what you mean - this sounds like a variation on what marketing science types call an adstock transformation. You can use a discrete delay, but I'd encourage you to make this a continuous process, because it's more realistic for people to gradually forget media exposure, than to have i...
by tomfid
Wed Jul 13, 2016 2:47 pm
Forum: Vensim
Topic: Sequential Project Portfolio
Replies: 3
Views: 2863

Re: Sequential Project Portfolio

I think this can be done in Vensim. The first step would be to build a single-project model. Then add an array dimension for the set of all projects. You end up simulating some zeroes (for projects that haven't started yet), but that's not much of a burden. Where Ventity would really help is with mu...
by tomfid
Wed Jul 13, 2016 1:05 pm
Forum: Vensim
Topic: Sequential Project Portfolio
Replies: 3
Views: 2863

Re: Sequential Project Portfolio

This sounds like the kind of thing we designed Ventity for.

I think the key question is, what does a project in the portfolio look like? Are you modeling it with full dynamic detail? Or just as a simple thing with specified duration, resources, etc.?
by tomfid
Wed Jul 13, 2016 12:56 am
Forum: Vensim
Topic: Graph Customization
Replies: 10
Views: 4379

Re: Graph Customization

vensim.ini is a file containing Vensim settings, including the fonts for custom graphs. (Fonts for tool graphs are in the toolset, which is a little easier to save & share.) If you run a .vpm in the Model Reader, it uses the vensim.ini embedded in the vpm. But if you run the same model in DSS, i...
by tomfid
Tue Jul 12, 2016 2:21 am
Forum: Vensim
Topic: vensim DLL with R
Replies: 12
Views: 7963

Re: vensim DLL with R

It seems like a strong candidate theory is that your command string is not getting passed as a c-format null terminated char*. It looks like as.raw() or as.character() might be the appropriate way to do that, but I don't see much good documentation on .c() (but again, the search problem in spades).
by tomfid
Tue Jul 12, 2016 2:18 am
Forum: Vensim
Topic: vensim DLL with R
Replies: 12
Views: 7963

Re: vensim DLL with R

Ugh. Usually if you hit the "back" button (ignoring the login request) it's all there still, and you can copy it before logging in. Sorry. You might try vensim_be_quiet, which takes a simple int argument, to see whether the issue is the argument format. (It looks like you'd have to pass th...
by tomfid
Tue Jul 12, 2016 2:06 am
Forum: Vensim
Topic: Graph Customization
Replies: 10
Views: 4379

Re: Graph Customization

See if this comes across with Arial-family fonts on the graphs:
LA Water Game 11 July DT Black TF.vpm
(35.25 KiB) Downloaded 196 times
by tomfid
Tue Jul 12, 2016 1:57 am
Forum: Vensim
Topic: Graph Customization
Replies: 10
Views: 4379

Re: Graph Customization

I see what you mean - your file doesn't come across with the new fonts.

One thing to try, while I look into it, and if you didn't already: before you create the .vpm, exit and relaunch Vensim. Then re-save the .vpm.
by tomfid
Mon Jul 11, 2016 10:03 pm
Forum: Vensim
Topic: Graph Customization
Replies: 10
Views: 4379

Re: Graph Customization

Cool setup! The settings are in two places: - For toolbar graphs, right-click the tool to edit settings, and use the font selections at the right of the dialog. - For custom graphs, the same options are in Tools>Options>Fonts2 If you need the tool settings to be portable across machines, you can eit...
by tomfid
Mon Jul 11, 2016 5:46 pm
Forum: Vensim
Topic: vensim DLL with R
Replies: 12
Views: 7963

Re: vensim DLL with R

The auto-export part is easy if you're using DSS, because you can run a postprocess command script to automatically export the dataset. Also, there are a lot more options for formatting in the latest release, including tidy data.
by tomfid
Mon Jul 11, 2016 3:04 pm
Forum: Vensim
Topic: vensim DLL with R
Replies: 12
Views: 7963

Re: vensim DLL with R

I'm pretty sure this has been done, but I don't recall where. Unfortunately "R" is hard to google. I'll ask around. It should be straightforward to write an R package that wraps Vensim, if it hasn't been done.
by tomfid
Thu Jul 07, 2016 3:49 am
Forum: Vensim
Topic: datasets seem to load but don't simulate
Replies: 4
Views: 2360

Re: datasets seem to load but don't simulate

Does your data contain a variable with a matching name? (One way to check for sure is to export the dataset to text and check the contents.)
by tomfid
Thu Jul 07, 2016 3:47 am
Forum: Vensim
Topic: Cumulate on future period
Replies: 2
Views: 1673

Re: Cumulate on future period

There's no general way to look into the future for non-data variables (that would be "acausal," i.e. no one actually knows the future). However, you can use arrays to create a virtual time dimension for future calculations. Or, in some cases, you can solve for the future trajectory analyti...
by tomfid
Mon Jul 04, 2016 3:12 pm
Forum: Ventity
Topic: use entities in new diagram
Replies: 4
Views: 4770

Re: use entities in new diagram

There are definitely some copy-paste issues, which I hope will be resolved in the next release.
by tomfid
Mon Jul 04, 2016 3:09 pm
Forum: Vensim
Topic: HEAVISIDE
Replies: 5
Views: 2706

Re: HEAVISIDE

It's hard to read your graph, but I think you should take a look at the output with the Table tool. I think you'll find that 1 and 2 are the only values, and the sloped lines are just an illusion from the linear interpolation on the graph.
by tomfid
Sun Jul 03, 2016 10:27 pm
Forum: Vensim
Topic: Sensitivity testing
Replies: 7
Views: 3375

Re: Sensitivity testing

One thing I notice is that you're pretty short on screen real estate. You might try reducing the icon size via Tools>Options>Toolbars. Then you can at least see if the tool is present.
by tomfid
Sun Jul 03, 2016 10:24 pm
Forum: Vensim
Topic: HEAVISIDE
Replies: 5
Views: 2706

Re: HEAVISIDE

STEP, PULSE etc. do create discrete responses. You may be getting the impression of a slope from plots that show a change happening over a TIME STEP, which is finite. The connecting line in these cases is a little misleading, because nothing is really defined between time steps. What are you seeing ...
by tomfid
Sat Jul 02, 2016 12:12 am
Forum: Vensim
Topic: Model CRASH Problem
Replies: 17
Views: 6921

Re: Model CRASH Problem

Another long shot idea would be to move it to your Documents folder or something like that.

I assume your system is running in English?

I'll try this new copy on my Win10 desktop.
by tomfid
Fri Jul 01, 2016 10:40 pm
Forum: Vensim
Topic: Model CRASH Problem
Replies: 17
Views: 6921

Re: Model CRASH Problem

I've followed both your sequences exactly, and unfortunately can't replicate the crash in either.

Can you try repeating one or both after setting a new, unique run name? That might give some hint as to whether this is a file access issue.
by tomfid
Fri Jul 01, 2016 1:53 pm
Forum: Vensim
Topic: Creating a Random Distribution on Every Run
Replies: 11
Views: 5972

Re: Creating a Random Distribution on Every Run

You can also use stream 0 for all the function calls, then set the global NOISE SEED parameter with the sensitivity control file.
by tomfid
Fri Jul 01, 2016 1:51 pm
Forum: Ventity
Topic: use entities in new diagram
Replies: 4
Views: 4770

Re: use entities in new diagram

Not quite sure what you're trying to do. Do you want to reuse the same structure in a different context (Paste as New, like Vensim's Replicate), or use a reference to existing structure (ordinary Paste)? Or reuse an entire entitytype?
by tomfid
Thu Jun 30, 2016 8:54 pm
Forum: Ventity
Topic: Use different table functions
Replies: 17
Views: 12276

Re: Use different table functions

I think that's the problem - you need the new June build 1123 - just visit http://vensim.com/ventity.html again.
by tomfid
Thu Jun 30, 2016 4:48 pm
Forum: Ventity
Topic: Use different table functions
Replies: 17
Views: 12276

Re: Use different table functions

What build date do you see in Help>About Ventity?