Search found 3808 matches
- Fri Jan 10, 2014 11:47 pm
- Forum: Vensim
- Topic: Problem with reading Data variable
- Replies: 6
- Views: 4518
Re: Problem with reading Data variable
Absolutely. That's how I learn too - a combination of seeing far by standing on the shoulders of giants, and good judgment = accumulated experience from bad judgment.
- Tue Dec 10, 2013 4:10 pm
- Forum: Vensim
- Topic: How to use Markov Chain Monte Carlo in Vensim?
- Replies: 33
- Views: 28074
Re: How to use Markov Chain Monte Carlo in Vensim?
I'm traveling, but hope to say a bit more about this soon.
- Tue Dec 10, 2013 4:09 pm
- Forum: Vensim
- Topic: Subscripts and Subranges
- Replies: 2
- Views: 2187
Re: Subscripts and Subranges
A more elegant solution (helpful if you need speed) is to use mapping. I think there's an example in the help system, but here's the idea: subrange : (x1-x100) previous : (x1-x99) -> next next : (x2-x100) -> previous var a[subrange] = .... sum of var a[x1] = var a[x1] sum of var a[next] = sum of var...
- Mon Nov 25, 2013 5:21 pm
- Forum: Vensim
- Topic: Order of execution of rates
- Replies: 5
- Views: 3163
Re: Order of execution of rates
Here's the sequence of computation:
http://www.vensim.com/documentation/ind ... quence.htm
http://www.vensim.com/documentation/ind ... quence.htm
- Tue Nov 19, 2013 11:19 pm
- Forum: Vensim
- Topic: Linking Vensim and Mathematica
- Replies: 15
- Views: 12005
Re: Linking Vensim and Mathematica
Correct. We'll probably change the API when the 64 bit version is finalized (beta release imminent). The limiting factor is that the .vdf format uses floats, so we need to provide a double .vdfx and matching function calls.
Tom
Tom
- Wed Nov 13, 2013 2:21 am
- Forum: Vensim
- Topic: Active Initial question, Vector function
- Replies: 9
- Views: 5760
Re: Active Initial question, Vector function
Even if there's no integration, there's a step at time=initial time, which sets up stock initial values (if there were any). That may produce the warning, because the initialization step produces a different random # from the dynamic step. I'm looking into the RNG in general, so there may be a way t...
- Tue Nov 12, 2013 12:30 am
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12739
Re: demand and supply at price
For a situation in which supply and demand are relatively constant, up to fixed willingness to pay/sell, you probably want a rectangular distribution (ptype=1) with a narrow pwidth (i.e. pwidth is smaller than the variation in prices across suppliers). Another possibility would be to use a linear pr...
- Mon Nov 11, 2013 7:32 pm
- Forum: Vensim
- Topic: Units error with MIN function
- Replies: 4
- Views: 5148
Re: Units error with MIN function
Great. Here's the intuition (for all watching this thread): First, a physical (conserved) stock always has to have negative feedback that forces the outflow to zero when the stock is zero, as in the reality check "no inventory -> no sales." If you write, outflow = MIN( stock, desired outfl...
- Sat Nov 09, 2013 2:59 am
- Forum: Vensim
- Topic: Units error with MIN function
- Replies: 4
- Views: 5148
Re: Units error with MIN function
I assume you have: outflow = MIN( water stock {gal} , indicated outflow {gal/yr} ) which is dimensionally inconsistent. What's really going on is that there's some characteristic time that it would take to drain the stock, given a pump or gravity or whatever operating as fast as possible: outflow = ...
- Fri Nov 08, 2013 11:48 pm
- Forum: Vensim
- Topic: Adding a subscript using elements of other subscript
- Replies: 6
- Views: 3295
Re: Adding a subscript using elements of other subscript
It may work with subranges (I don't recall), but I think that's not quite the issue. You have several instances of mixed subscript uses - for example: vector reorder(Desired expansion x hour[HOUR,EXPN2],price order inc[HOUR,TECH]) I think it's checking the size of the TECH family (=PDC) against EXPN...
- Fri Nov 08, 2013 7:34 pm
- Forum: Vensim
- Topic: Adding a subscript using elements of other subscript
- Replies: 6
- Views: 3295
Re: Adding a subscript using elements of other subscript
A function you've used may be expecting a complete range rather than a subrange, and the addition of the new subscript converts TECH to a subrange. Hard to tell without an example though.
- Fri Nov 08, 2013 6:53 pm
- Forum: Vensim
- Topic: Adding a subscript using elements of other subscript
- Replies: 6
- Views: 3295
Re: Adding a subscript using elements of other subscript
Are you using a VECTOR REORDER with PDC on the LHS and Tech on the RHS of the equation?
Hard to tell without seeing the equations in question.
Hard to tell without seeing the equations in question.
- Fri Nov 08, 2013 5:06 pm
- Forum: Vensim
- Topic: Is it possible to define the end point of Spread Sheet data
- Replies: 4
- Views: 2786
Re: Is it possible to define the end point of Spread Sheet d
You could try playing around with named ranges. There's an example of usage in the help system for the GET XLS functions. I don't remember off the top of my head whether it's possible to use that to limit the data range, but it might work. The downside is that named ranges are invisible in Excel. Th...
- Thu Nov 07, 2013 2:32 pm
- Forum: Vensim
- Topic: Error with LOOKUP
- Replies: 5
- Views: 2927
Re: Error with LOOKUP
Ahh ... i'd forgotten, but there's a bug in the labeling of the fields in the equation editor, which may have misled you. You have: with lookup.JPG but the WITH LOOKUP on the RHS is not needed, because that's already taken care of by the choice of equation type with the dropdown menus. You need: wit...
- Thu Nov 07, 2013 2:00 am
- Forum: Vensim
- Topic: Active Initial question, Vector function
- Replies: 9
- Views: 5760
Re: Active Initial question, Vector function
Have you tried checking the initialization step results by using Diff integration?
- Thu Nov 07, 2013 12:41 am
- Forum: Vensim
- Topic: Error with LOOKUP
- Replies: 5
- Views: 2927
Re: Error with LOOKUP
You probably have an extra parentheses in one of the fields in the equation editor. We can't tell without a copy of the model, or perhaps a screenshot of the equation in the editor, so if you can post one of those we can help.
- Mon Nov 04, 2013 4:40 pm
- Forum: Vensim
- Topic: Population growth 'units' error
- Replies: 4
- Views: 4117
Re: Population growth 'units' error
It appears that the problem is the dimensions of your lookup: population growth rate lookup --> Year If you change this to 1/year or fraction/year, it should work. Note that the units on a lookup represent the output, rather than the input. It's often good practice to normalize the inputs and output...
- Fri Nov 01, 2013 2:31 am
- Forum: Vensim
- Topic: Allocate by priority with 3 subscripts
- Replies: 2
- Views: 2190
Re: Allocate by priority with 3 subscripts
I'm not sure this is what you want though, because the alloc will happen across TECH but not HEXP. If you want to allocate over TECH and HEXP at the same time, you'll have to create a single dimension containing all the [TECH,HEXP] combinations.
- Fri Nov 01, 2013 2:25 am
- Forum: Vensim
- Topic: Allocate by priority with 3 subscripts
- Replies: 2
- Views: 2190
Re: Allocate by priority with 3 subscripts
The ALLOC functions work across the last subscript, so if you're allocating across producers, you need to reorder Expected supply[HOUR,TECH,HEXP] as Expected supply[HOUR,HEXP,TECH]. See attached.
- Thu Oct 31, 2013 3:28 pm
- Forum: Vensim
- Topic: Model Variable tool and Merge tools missing
- Replies: 3
- Views: 2333
Re: Model Variable tool and Merge tools missing
This is actually a deliberate design decision in PLE, in order to ensure that the diagram corresponds exactly to the equations, and that each variable has a single, primary home view. Pro/DSS provide more flexibility, including text-only models.
- Wed Oct 30, 2013 2:30 am
- Forum: Vensim
- Topic: about model time step setting and function use
- Replies: 5
- Views: 4053
Re: about model time step setting and function use
There does appear to be a storage or display issue with the GET XLS variable in gaming mode. However, if you add an auxiliary, b=a, it takes on the correct values, so I think the underlying sim is OK. I'll investigate further.
- Wed Oct 30, 2013 2:23 am
- Forum: Vensim
- Topic: about model time step setting and function use
- Replies: 5
- Views: 4053
Re: about model time step setting and function use
I think what you're seeing is a consequence of the settings in the Scaling tab of the Control Panel. however, I'm not sure you'll be able to make a choice that's satisfactory at all possible times. Is this a Venapp or a regular model?
I'll take a look at your example.
I'll take a look at your example.
- Tue Oct 29, 2013 2:20 pm
- Forum: Vensim
- Topic: DATA variable name
- Replies: 2
- Views: 2224
Re: DATA variable name
It's probably not what you're looking for, but data sources for variables in calibrations are listed in the payoff report (runname.rep).
- Tue Oct 29, 2013 1:33 am
- Forum: Vensim
- Topic: Problems when reordering vectors
- Replies: 5
- Views: 3111
Re: Problems when reordering vectors
Here's your problem: when i use direction=0, the result is wrong (2,0,1;2,0,1). It is cleat that the correct answer should be 1,2,0;1,2,0 This is true if 1,2,0 represents the positions of each element in the sorted array. So, if the input is 3,2,4, the 0 in the third element would indicate that the ...
- Tue Oct 29, 2013 12:38 am
- Forum: Vensim
- Topic: Problems when reordering vectors
- Replies: 5
- Views: 3111
Re: Problems when reordering vectors
When I use 0 in the version that I posted, I get
... which looks OK. Am I missing something?
Code: Select all
Array output format
"sorted price[HOUR,TECH]" at time 5 Runs: Current
sorted price[HOUR,TECH] P1 P2 P3
H1 4 3 2
H2 7 6 5