Transposing is easy - just do something like:
y[a,b] = x[b,a]
Search found 3808 matches
- Mon Sep 12, 2016 9:10 pm
- Forum: Vensim
- Topic: Reordering a matrix
- Replies: 3
- Views: 2577
- Mon Sep 12, 2016 7:59 pm
- Forum: Vensim
- Topic: the last value of a variable
- Replies: 2
- Views: 1955
Re: the last value of a variable
If you want the value in the immediately previous time step, you can store it in a stock, or use DELAY FIXED with a lag of TIME STEP. SMOOTH works too, as long as you're using Euler integration.
- Mon Sep 12, 2016 2:58 pm
- Forum: Vensim
- Topic: Getting a string from a VDF
- Replies: 9
- Views: 9320
Re: Getting a string from a VDF
Could you encode the string information as numbers, or are they ad hoc and numerous?
- Mon Sep 12, 2016 1:06 pm
- Forum: Vensim
- Topic: Long vector reordering
- Replies: 3
- Views: 2115
Re: Long vector reordering
Also, check the help - there's a sample model attached to the VECTOR SORT topic in the manual.
- Sat Sep 10, 2016 2:43 pm
- Forum: Vensim
- Topic: capture daily values from excel
- Replies: 18
- Views: 8963
Re: capture daily values from excel
You can't initialize the internal state of a queue with that level of detail. How many sheep do you have? An array of individuals might be a viable alternative. (If you have a lot, Ventity might be even better.) For your inventory-age-labor example, that sounds like a classic aging chain, which coul...
- Fri Sep 09, 2016 2:24 pm
- Forum: Vensim
- Topic: Linear Program
- Replies: 14
- Views: 7513
Re: Linear Program
Cool. When I first wrote the code, I had at least two ambitions that remain unrealized: - use the LP infrastructure to create some custom allocation functions. For example, the LP makes it easy to solve the many-to-many noncommodity allocation problem, with unique costs (e.g. shipping) for each supp...
- Thu Sep 08, 2016 3:08 pm
- Forum: Vensim
- Topic: Linear Program
- Replies: 14
- Views: 7513
Re: Linear Program
I think the external lib may need to be complied with the flag DPMATH so that it's variable types are compatible with DP Vensim. I don't recall the details, but I'm hoping Tony does.
- Thu Sep 08, 2016 2:39 pm
- Forum: Vensim
- Topic: documentation multicontext.dll
- Replies: 3
- Views: 2322
Re: documentation multicontext.dll
We're happy to supply a quote if you need it.
It actually is technically possible to create a client-side .dll for several platforms (Win, Mac, Linux, iOS); we don't have off-the-shelf licensing for those but could discuss it.
It actually is technically possible to create a client-side .dll for several platforms (Win, Mac, Linux, iOS); we don't have off-the-shelf licensing for those but could discuss it.
- Wed Sep 07, 2016 11:53 pm
- Forum: Ventity
- Topic: September 27 - Ventity Beta E30
- Replies: 0
- Views: 4757
September 27 - Ventity Beta E30
The latest beta is #E30, September 27th. Get it at http://vensim.com/ventity-beta/ . We're preparing for commercial release, so this version is testing licensing infrastructure. For the moment, this could hardly be easier - just click the "Continue Evaluation" button when you start up the ...
- Mon Sep 05, 2016 1:50 pm
- Forum: Vensim
- Topic: Vensim slow even after off-on
- Replies: 2
- Views: 2065
Re: Vensim slow even after off-on
Can you post or email us the model? It might just be size, not be a platform issue.
- Mon Sep 05, 2016 1:49 pm
- Forum: Vensim
- Topic: Maximum and average
- Replies: 11
- Views: 5567
Re: Maximum and average
The reason you can't retrieve values of variables ahead of time in Vensim is that this creates an acausal model. No one can really look into the future; they have expectations of the future, not knowledge. Normally the right way to solve the problem is to model those expectations explicitly. If you ...
- Mon Sep 05, 2016 1:44 pm
- Forum: Vensim
- Topic: Initialize from last run?
- Replies: 7
- Views: 4636
Re: Initialize from last run?
How have you changed the time parameters? If you use Model>Settings, you're changing the model. You can make runtime changes with via the various constant setting methods. For reuse, I would normally put the modified values in a .cin file that could be loaded as needed.
- Mon Sep 05, 2016 1:41 pm
- Forum: Vensim
- Topic: How to use Vensim for programming a do-while loop
- Replies: 7
- Views: 4190
Re: How to use Vensim for programming a do-while loop
Create an array dimension for the projects, and use SUM(value[project!]) to add them up. https://www.vensim.com/documentation/fn_sum.htm Set the value to 0 for projects that are inactive. If you're not familiar with declarative languages like Vensim, you should probably work through the User Guide, ...
- Mon Sep 05, 2016 1:36 pm
- Forum: Vensim
- Topic: the optimization of the share of electricity generation mix of UK
- Replies: 6
- Views: 3231
Re: the optimization of the share of electricity generation mix of UK
There have been several recent threads on this. See http://www.ventanasystems.co.uk/forum/viewtopic.php?f=2&t=6388&p=22779&hilit=VECTOR+LOOKUP#p22779 and http://www.ventanasystems.co.uk/forum/viewtopic.php?f=2&t=6349 The optimizer only works on constants; you can use VECTOR LOOKUP to...
- Wed Aug 31, 2016 2:35 pm
- Forum: Vensim
- Topic: Maximum and average
- Replies: 11
- Views: 5567
Re: Maximum and average
average x = SMOOTH(x,interval) gives an exponentially weighted moving average of x with mean horizon of interval.
If you need 0s in between, you can use something like:
avg or 0 = IF THEN ELSE( PULSE TRAIN(initial time, time step, interval, final time), average x, 0 )
If you need 0s in between, you can use something like:
avg or 0 = IF THEN ELSE( PULSE TRAIN(initial time, time step, interval, final time), average x, 0 )
- Mon Aug 29, 2016 11:32 pm
- Forum: Vensim
- Topic: Saved Results vs TimeStep Results
- Replies: 5
- Views: 3494
Re: Saved Results vs TimeStep Results
The PULSE TRAIN(INITIAL TIME, TIME STEP, SAVEPER, FINAL TIME) creates a signal variable that is zero most of the time, and 1 at intervals equal to SAVEPER (assuming that SAVEPER=500). If you also want to capture a value only when IRE > 1, you can just add that to the condition with :AND:.
- Mon Aug 29, 2016 8:10 pm
- Forum: Vensim
- Topic: Saved Results vs TimeStep Results
- Replies: 5
- Views: 3494
Re: Saved Results vs TimeStep Results
You could use SAMPLE IF TRUE to sample the value of the variable every 500 units. Something like:
saved x = SAMPLE IF TRUE( PULSE TRAIN(INITIAL TIME, TIME STEP, SAVEPER, FINAL TIME), actual x, actual x )
saved x = SAMPLE IF TRUE( PULSE TRAIN(INITIAL TIME, TIME STEP, SAVEPER, FINAL TIME), actual x, actual x )
- Mon Aug 29, 2016 8:06 pm
- Forum: Ventity
- Topic: cohort modeling examples
- Replies: 21
- Views: 15690
Re: cohort modeling examples
This turns out to be quite tricky. I ran the model with 5 and 10 year cohorts, and got quite different results. The difference emerges with births from the earliest created cohorts (not the preexisting ones in the data). Here's the sum of births: births.png The difference arises from the timing of t...
- Mon Aug 29, 2016 3:17 pm
- Forum: Ventity
- Topic: cohort modeling examples
- Replies: 21
- Views: 15690
Re: cohort modeling examples
I think the answer probably has to do with the granularity of the input data, but I'll have to fire it up and take a look to be sure.
- Mon Aug 29, 2016 3:07 pm
- Forum: Vensim
- Topic: Sensitivity Simulation Setup
- Replies: 6
- Views: 3592
Re: Sensitivity Simulation Setup
If you're using Grid with VECTOR, order won't matter, because the setup is nonrandom. The order of the simulations might vary, but the same set will be run. Exporting the run to view the data directly is a good check. Documentation is here https://www.vensim.com/documentation/sensitivity.htm Every d...
- Mon Aug 29, 2016 2:55 pm
- Forum: Vensim
- Topic: Maximum and average
- Replies: 11
- Views: 5567
Re: Maximum and average
For the Max, see the first example in https://www.vensim.com/documentation/fn_sample_if_true.htm Also: http://www.ventanasystems.co.uk/forum/viewtopic.php?f=2&t=6366&hilit=SAMPLE+IF+TRUE For the moving average, you can build a structure like: average X = Sum X / Averaging Period Units: stuff...
- Sat Aug 27, 2016 2:22 am
- Forum: Vensim
- Topic: optimization in vensim based on time
- Replies: 6
- Views: 4494
Re: optimization in vensim based on time
You need to specify:
0<=suppliers' Order Amount[supplier]<=70000
0<=suppliers' Order Amount[supplier]<=70000
- Fri Aug 26, 2016 11:31 pm
- Forum: Vensim
- Topic: The largest number vensim can calculate.
- Replies: 2
- Views: 1752
Re: The largest number vensim can calculate.
That's the special value for :NA:. https://www.vensim.com/documentation/index.html?na.htm
The largest ordinary value is about +/- 3 x 10^38.
In double precision Vensim DSS the largest value is about 2 x 10^308.
The largest ordinary value is about +/- 3 x 10^38.
In double precision Vensim DSS the largest value is about 2 x 10^308.
- Fri Aug 26, 2016 10:38 pm
- Forum: Vensim
- Topic: Problem with INVERT MATRIX
- Replies: 4
- Views: 2608
Re: Problem with INVERT MATRIX
Can you post a sample model?
Have you tried double precision Vensim DSS?
Have you tried double precision Vensim DSS?
- Fri Aug 26, 2016 2:08 pm
- Forum: Vensim
- Topic: optimization in vensim based on time
- Replies: 6
- Views: 4494
Re: optimization in vensim based on time
You'll need to attach the .voc and .vpd files for a diagnosis.
If a variable is subscripted in the model, it must also be subscripted in the control files.
If a variable is subscripted in the model, it must also be subscripted in the control files.