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by tomfid
Mon Jul 24, 2023 1:10 am
Forum: Vensim
Topic: a simple example of my gnarly IF THEN ELSE problem (bug?)
Replies: 8
Views: 641

Re: a simple example of my gnarly IF THEN ELSE problem (bug?)

Correct - no - because then there would be no value to assign to the LHS.
by tomfid
Mon Jul 24, 2023 1:08 am
Forum: Vensim
Topic: a gnarly IF THEN ELSE problem
Replies: 9
Views: 959

Re: a gnarly IF THEN ELSE problem

Your translation has two clauses for # if false that Time-sy <= 0 - you can get rid of the second q = 1 ), Then it can be implemented as q = IF THEN ELSE( pE < w , {# if true that pE < w} IF THEN ELSE( Time-sy <= 0 , {# if true that Time-sy <= 0} {q =} 1 , {# if false that Time-sy <= 0} IF THEN ELSE...
by tomfid
Mon Jul 24, 2023 12:32 am
Forum: Vensim
Topic: a simple example of my gnarly IF THEN ELSE problem (bug?)
Replies: 8
Views: 641

Re: a simple example of my gnarly IF THEN ELSE problem (bug?)

The only assignment in Vensim is to the left hand side variable. If you want to make multiple assignments, you can use distinct variables, or subscript elements. You can't make multiple assignments within a single equation.
by tomfid
Mon Jul 24, 2023 12:28 am
Forum: Vensim
Topic: a gnarly IF THEN ELSE problem
Replies: 9
Views: 959

Re: a gnarly IF THEN ELSE problem

The Vensim language doesn't support that kind of procedural code. I'm not sure it improves readability over nesting.
by tomfid
Sun Jul 23, 2023 7:33 pm
Forum: Vensim
Topic: Start new models failed
Replies: 15
Views: 1026

Re: Start new models failed

I hope this means it's working?
by tomfid
Sun Jul 23, 2023 7:31 pm
Forum: Vensim
Topic: a gnarly IF THEN ELSE problem
Replies: 9
Views: 959

Re: a gnarly IF THEN ELSE problem

I think your simplification is incorrect, because it doesn't nest. It should look li

IF THEN ELSE( a=b, c
, IF THEN ELSE( d=e, f, g)
)
by tomfid
Sun Jul 23, 2023 7:27 pm
Forum: Vensim
Topic: a simple example of my gnarly IF THEN ELSE problem (bug?)
Replies: 8
Views: 641

Re: a simple example of my gnarly IF THEN ELSE problem (bug?)

This kind of looks like procedural code in the equation field. You can't do that, by design.

100
c*d

is read as

100 c*d

(after condensing the whitespace).

This would have to be

100 <operator> c*d

where <operator> is + - * / ^ in order to make sense.
by tomfid
Sun Jul 23, 2023 7:17 pm
Forum: Vensim
Topic: Start new models failed
Replies: 15
Views: 1026

Re: Start new models failed

2023-07-23_13-16-19.png
2023-07-23_13-16-19.png (9.56 KiB) Viewed 927 times
We split it into two ... won't update the video until later, because there's a big update for these tools in the pipeline.
by tomfid
Fri Jul 21, 2023 2:22 pm
Forum: Vensim
Topic: Start new models failed
Replies: 15
Views: 1026

Re: Start new models failed

Not having seen this before, I'm pretty stumped. When the pred-prey model opened, could you interact with it? "PL9999" is the standard s/n for all academic PLE, so unfortunately that doesn't provide a clue. Long shot, but anything unusual about the environment? (multiple monitors, remote a...
by tomfid
Fri Jul 21, 2023 1:33 pm
Forum: Vensim
Topic: Exporting large sensitivity output
Replies: 2
Views: 444

Re: Exporting large sensitivity output

You could use a savelist or SAVEPER to reduce the scale of the data.

You could also try the relational Data List format or .dat (though the latter is not really friendly to other apps). Both will be large.

.tab is probobly no better, and .xls is surely worse.
by tomfid
Thu Jul 20, 2023 5:27 pm
Forum: Ventity
Topic: GIS in Ventity
Replies: 1
Views: 1492

Re: GIS in Ventity

There isn't ... but I'll create something after the SD conference.
by tomfid
Thu Jul 20, 2023 5:02 pm
Forum: Vensim
Topic: v.10 Parallel computations
Replies: 2
Views: 812

Re: v.10 Parallel computations

You can use the DSS trial key on the conference page if you'd like to experiment.

https://vensim.com/conference/
by tomfid
Thu Jul 20, 2023 4:28 pm
Forum: Vensim
Topic: Delay Function cannot shut off flow using a test for negative stock level.
Replies: 18
Views: 3987

Re: Delay Function cannot shut off flow using a test for negative stock level.

Well I must be dumb too, because I hadn't figured it out yet either!

I generally prefer the array version over the conveyor function. It's more flexible, because you can have multiple outflows (separate decay and uptake, for example), or nonlinear uptake.
by tomfid
Thu Jul 20, 2023 3:06 pm
Forum: Vensim
Topic: Start new models failed
Replies: 15
Views: 1026

Re: Start new models failed

I can't immediately think of a reason. My OS versions (13.1 and 10.something) bracket yours, and PLE works fine on both. The only thing I can think of is an expired evaluation license, but normally the application declines to start rather than freezing. Solution would be to reinstall using the educa...
by tomfid
Tue Jul 18, 2023 4:28 pm
Forum: Vensim
Topic: Delay Function cannot shut off flow using a test for negative stock level.
Replies: 18
Views: 3987

Re: Delay Function cannot shut off flow using a test for negative stock level.

In this case, I think you can forget about my rigid and elastic pipe variants, and just use the classic aging chain. There are two options for this: - If the loss function is a simple fractional rate (uptake, or radioactive decay), you can use the DELAY CONVEYOR with leakage. There's an example inst...
by tomfid
Mon Jul 03, 2023 2:59 pm
Forum: Vensim
Topic: DBLPREC
Replies: 8
Views: 3354

Re: DBLPREC

I think this thread viewtopic.php?t=8116 established that the error is caused by a missing : at the beginning of a macro.
by tomfid
Mon Jul 03, 2023 2:55 pm
Forum: Vensim
Topic: DBLPREC
Replies: 8
Views: 3354

Re: DBLPREC

Rather than defining these in the code, you probably want to define them in the preprocessor, via /D "DBLPREC". In Visual Studio this is in project properties>C/C++>Preprocessor.
by tomfid
Mon Jul 03, 2023 2:51 pm
Forum: Vensim
Topic: Active initial differences help
Replies: 3
Views: 765

Re: Active initial differences help

The warning arises because the random draw differs between the initialization step and the first dynamic time step. However, since this is not an ACTIVE INITIAL variable, I don't think it should be reporting this. I think the trigger is, as Admin suggests, that there's too much nesting in: Ingresos ...
by tomfid
Mon Jul 03, 2023 2:40 pm
Forum: Vensim
Topic: Error when using 'check model'
Replies: 3
Views: 1415

Re: Error when using 'check model'

The precision of the dll has to match the precision of the Vensim version in use. All Vensim versions are now double precision.
by tomfid
Fri Jun 30, 2023 8:32 pm
Forum: Vensim
Topic: SyntheSim doesn't work
Replies: 2
Views: 761

Re: SyntheSim doesn't work

There have been problems with cloud services locking files in the past, but I don't think OneDrive is likely to be the cause. I use it all the time without issues.
by tomfid
Fri Jun 30, 2023 6:22 pm
Forum: Vensim
Topic: Delay Function cannot shut off flow using a test for negative stock level.
Replies: 18
Views: 3987

Re: Delay Function cannot shut off flow using a test for negative stock level.

A question: is the intestine really like a plug flow reactor? As I understand it, those take off material only at the end. What little I know about the intestine suggests that there's a lot of material exchange along the way. Also, it's elastic and has active transport, right? Anyway, here are some...
by tomfid
Thu Jun 29, 2023 1:32 pm
Forum: Vensim
Topic: Delay Function cannot shut off flow using a test for negative stock level.
Replies: 18
Views: 3987

Re: Delay Function cannot shut off flow using a test for negative stock level.

Because the intestine might have complex dynamics for each segment, and it's central to the model, I'm going to suggest that you use arrays rather than delays. I'll post an example. A question: is the intestine really like a plug flow reactor? As I understand it, those take off material only at the ...
by tomfid
Thu Jun 29, 2023 1:12 pm
Forum: Vensim
Topic: Customer satisfaction model (5 Service quality dimensions)
Replies: 6
Views: 1123

Re: Customer satisfaction model (5 Service quality dimensions)

For customers, your INTEG expression is, IF THEN ELSE((Number of Customers-Previous Customer)>=0, Customer Retention-Customer Turnover-Previous Customer*Customer Units,0) since previous customer = number of customers, this simplifies to just Customer Retention-Customer Turnover-Previous Customer*Cus...
by tomfid
Thu Jun 29, 2023 1:51 am
Forum: Vensim
Topic: Customer satisfaction model (5 Service quality dimensions)
Replies: 6
Views: 1123

Re: Customer satisfaction model (5 Service quality dimensions)

There are two nonstandard uses of stocks here: the "previous" inputs to customer satisfaction and number of customers. I think you should revert to standard notation, where the only things affecting the integrations in stocks are flows (plus the initial state). For customer satisfaction, y...
by tomfid
Wed Jun 28, 2023 7:34 pm
Forum: Vensim
Topic: optimization
Replies: 12
Views: 3638

Re: optimization

There are a couple other ways to solve this problem, closely related to VECTOR LOOKUP: https://metasd.com/2018/02/polynomials-interpolating-functions-decision-rules/ The reason you don't see this done much is that decision rules that are based on a vector of time points are not very general. They so...