Search found 3800 matches
- Fri May 04, 2012 2:41 pm
- Forum: Vensim
- Topic: problem moving around the arrows on a model's sketch
- Replies: 2
- Views: 1875
Re: problem moving around the arrows on a model's sketch
I think the first issue occurs because the big view is scaled to fit the screen, while the others are at 100%. So, regrettably, there probably isn't a way to get the arrowheads to match. The second is probably also exacerbated by scaling, but clearly it would help if we made the hot spot for arrow h...
- Fri May 04, 2012 2:11 pm
- Forum: Vensim
- Topic: What improvements would you like to see in Vensim?
- Replies: 150
- Views: 10429855
Keep the ideas coming!
Some of these things will take a while, but we're listening.
- Mon Apr 23, 2012 11:27 pm
- Forum: Vensim
- Topic: Can Vensim work with 64 Bit Excel?
- Replies: 3
- Views: 3361
Re: Can Vensim work with 64 Bit Excel?
The other open question is whether you can call the (32 bit) dll from a VB script in a 64 bit app. Some 32/64 mixed environments don't work - for example, you can't call a 32 bit JNI dll from a 64 bit virtual machine in Java.
Tom
Tom
- Thu Apr 19, 2012 2:42 pm
- Forum: Vensim
- Topic: Annualizing 6 month output
- Replies: 4
- Views: 3904
Re: Annualizing 6 month output
The answer partly depends on whether your model has units of years, with time step = 0.5, or months with time step = 6. If you're running in years, flows already have instantaneous annualized values, so you don't need to do anything unless you need to capture the actual reporting lag involved in ann...
- Fri Apr 13, 2012 1:36 pm
- Forum: Vensim
- Topic: What does this error message mean?
- Replies: 5
- Views: 5440
Re: What does this error message mean?
We're working on it.
I don't think it'll help with memory, but if your arrays are sparse, VECTOR SELECT can help quite a bit with execution time.
I don't think it'll help with memory, but if your arrays are sparse, VECTOR SELECT can help quite a bit with execution time.
- Fri Apr 13, 2012 1:35 pm
- Forum: Vensim
- Topic: Equation editor hangs programme
- Replies: 19
- Views: 14955
Re: Equation editor hangs programme
Not sure why this is happening. The error files are unfortunately uninformative (at least to me). What operating system version are you using? One thing to try would be simply deleting (or renaming) the vensim.ini file mentioned in Tony's March 4 post (Vensim should recreate a fresh one on startup)....
- Thu Apr 12, 2012 11:30 pm
- Forum: Vensim
- Topic: Confusing error
- Replies: 1
- Views: 1578
Re: Confusing error
This error is generated when you're using all the elements of an array, but not computing some of them. For example: myrange : mysubA, mysubB mysubA : (sa1-sa10) mysubB : (sb1-sb10) datavar[mysubA] := GET XLS DATA( ... ) auxvar[myrange] = 3*datavar[myrange] Notice that above, datavar is used with [m...
- Thu Apr 12, 2012 11:26 pm
- Forum: Vensim
- Topic: What does this error message mean?
- Replies: 5
- Views: 5440
Re: What does this error message mean?
You may be limited by your largest array block - what number does it give with the "insufficient memory" error? (I'm guessing somewhere upward of 500 megabytes)
- Wed Apr 11, 2012 8:12 pm
- Forum: Vensim
- Topic: What does this error message mean?
- Replies: 5
- Views: 5440
Re: What does this error message mean?
When does it happen?
It could be that your model is too big to be executed. Check Model>Settings>Info and see how many equations there are.
Tom
It could be that your model is too big to be executed. Check Model>Settings>Info and see how many equations there are.
Tom
- Tue Apr 10, 2012 5:02 pm
- Forum: Vensim
- Topic: Equation editor hangs programme
- Replies: 19
- Views: 14955
Re: Equation editor hangs programme
Is there a particular model that offends, that you can post?
- Tue Apr 03, 2012 2:46 am
- Forum: Vensim
- Topic: Insufficient memory in Vensim
- Replies: 6
- Views: 3908
Re: Insufficient memory in Vensim
194k should not be a problem - it might be a little slow, but not terrible - unless your time range is very large. For example, if your (FINAL TIME-INITIAL TIME)/TIME STEP is much greater than 10,000 that might be an issue. However, if the info says, "cannot be simulated," you have a synta...
- Mon Apr 02, 2012 9:16 pm
- Forum: Vensim
- Topic: Insufficient memory in Vensim
- Replies: 6
- Views: 3908
Re: Insufficient memory in Vensim
Do you mean ranges with 3 elements (like city : boston, denver, chicago ) or variables with 3 ranges (like price[commodity,city,flavor])? If it's the latter, your model may be very large. A variable with 6 ranges will have N^6 elements, where N is the dimension of each range. If N=10, for example, y...
- Mon Apr 02, 2012 8:05 pm
- Forum: Vensim
- Topic: moving backward in games with delays
- Replies: 2
- Views: 1864
Re: moving backward in games with delays
Noted. Thanks!
I haven't tried it, but it might be possible to store the decisions from a game in a .gin file, and then restart from the beginning and run up to the desired point using the .gin. Computationally wastefull, but maybe OK?
I haven't tried it, but it might be possible to store the decisions from a game in a .gin file, and then restart from the beginning and run up to the desired point using the .gin. Computationally wastefull, but maybe OK?
- Tue Mar 27, 2012 9:29 pm
- Forum: Vensim
- Topic: Over Allocation
- Replies: 4
- Views: 4095
Re: Over Allocation
This kind of problem can be pretty messy (which is why it takes an iterative solver, as in Excel). It would be very natural to solve as a linear program. Mechanically, your model has 2 issues, fixed below. First, you're feeding in [problem,collect] tasks at the left, where it should probably be just...
- Tue Mar 27, 2012 2:56 pm
- Forum: Vensim
- Topic: Over Allocation
- Replies: 4
- Views: 4095
Re: Over Allocation
Have you checked the example in the Help system, Ch. 4, Reference Manual, functions?
ALLOCATE AVAILABLE isn't designed for many-to-many situations (Relays -> Collects) so the behavior you're getting sounds right. I think we need to debug your FIND MARKET PRICE version.
ALLOCATE AVAILABLE isn't designed for many-to-many situations (Relays -> Collects) so the behavior you're getting sounds right. I think we need to debug your FIND MARKET PRICE version.
- Mon Mar 26, 2012 11:11 pm
- Forum: Vensim
- Topic: ODBC Problems (Connecting Vensim to MS Access)
- Replies: 8
- Views: 7544
Re: ODBC Problems (Connecting Vensim to MS Access)
This is great. I posted it to a few places. http://blog.metasd.com/2012/03/vensim-data-with-odbc/ http://www.facebook.com/pages/Vensim/131233120248692 Thanks!
- Mon Mar 26, 2012 5:57 pm
- Forum: Vensim
- Topic: Kernel density estimation
- Replies: 8
- Views: 4095
Re: Kernel density estimation
OK. I think my example should work for you.
- Mon Mar 26, 2012 4:34 pm
- Forum: Vensim
- Topic: Kernel density estimation
- Replies: 8
- Views: 4095
Re: Kernel density estimation
Here's an example:
I haven't double checked to be sure that the resulting pdf integrates to 1, but it should be OK.- Mon Mar 26, 2012 3:34 pm
- Forum: Vensim
- Topic: Kernel density estimation
- Replies: 8
- Views: 4095
Re: Kernel density estimation
OK - I think this is actually fairly easy. I'll post an example. One more question though: once you have the kernel-smoothed density, what will you do with it? For example, do you want to pick arbitrary points from it, or generate incomes at uniformly-spaced levels, essentially using the pdf as an i...
- Mon Mar 26, 2012 1:29 pm
- Forum: Vensim
- Topic: error messages related to lookups
- Replies: 10
- Views: 10856
Re: error messages related to lookups
Specifically, see:
http://www.vensim.com/documentation/fn_lookup_area.htm
There's a chapter in the User's Guide on lookups:
http://www.vensim.com/documentation/usr08.htm
For iThink users, the WITH LOOKUP syntax may be more familiar:
http://www.vensim.com/documentation/fn_with_lookup.htm
http://www.vensim.com/documentation/fn_lookup_area.htm
There's a chapter in the User's Guide on lookups:
http://www.vensim.com/documentation/usr08.htm
For iThink users, the WITH LOOKUP syntax may be more familiar:
http://www.vensim.com/documentation/fn_with_lookup.htm
- Sun Mar 25, 2012 6:19 pm
- Forum: Vensim
- Topic: how to perform a convolution in vensim
- Replies: 17
- Views: 12403
Re: how to perform a convolution in vensim
It's using the profile and the delay time together to normalize the pdf and establish the mean time. Off the top of my head, I believe that the procedure is (a) integrate x*lookup(x) over the range of the lookup, and divide by the range, to determine the mean arrival time in the lookup (b) rescale t...
- Sun Mar 25, 2012 2:18 am
- Forum: Vensim
- Topic: error messages related to lookups
- Replies: 10
- Views: 10856
Re: error messages related to lookups
Vensim differs from iThink in that a lookup can be used in more than one place, so the lookup table is separate from the input and expressions that use the input. In that respect it is more like DYNAMO. In DYNAMO you might write: FCAOR = TABHL( FCAORT, NRFR, 0, 1, .1 ) FCAORT = 1/.9/.7/.5 ... (borro...
- Sat Mar 24, 2012 5:26 pm
- Forum: Vensim
- Topic: how to perform a convolution in vensim
- Replies: 17
- Views: 12403
Re: how to perform a convolution in vensim
Incidentally, if there's some other software you use that does things differently/better, we're always interested to hear about it.
- Sat Mar 24, 2012 5:25 pm
- Forum: Vensim
- Topic: how to perform a convolution in vensim
- Replies: 17
- Views: 12403
Re: how to perform a convolution in vensim
I'll take a look. If you don't need 'init' and 'init grow' you can set them to 0. The profile and delay time parameters work together. The profile gives the shape of the distribution. It's then scaled so that (a) the area under the curve is 1 and (b) the mean arrival time is equal to the delay time ...
- Sat Mar 24, 2012 4:28 pm
- Forum: Vensim
- Topic: Kernel density estimation
- Replies: 8
- Views: 4095
Re: Kernel density estimation
Are you trying to smooth across time, or income values, or both?
If this is all you're doing, you'd be better off using a stats package. But if this is part of a dynamic model, we can probably come up with a strategy that works.
Tom
If this is all you're doing, you'd be better off using a stats package. But if this is part of a dynamic model, we can probably come up with a strategy that works.
Tom