Search found 137 matches

by RWTH_FCN
Fri Mar 06, 2020 10:41 am
Forum: Vensim
Topic: Question about deleting previous runs
Replies: 4
Views: 371

Re: Question about deleting previous runs

Administrator wrote:
Fri Mar 06, 2020 10:37 am
If you close Vensim, you will be able to delete them manually.
Ah, you are right. thanks
by RWTH_FCN
Fri Mar 06, 2020 10:26 am
Forum: Vensim
Topic: Question about deleting previous runs
Replies: 4
Views: 371

Re: Question about deleting previous runs

What version of Vensim are you using? You can always delete them manually as well by browsing to the folder where they are stored. Version 6.4. Actually, when I want to delete them manually I get an error that they cannot be deleted becasue file is open in Vensim. So, I decided to remove them in Ve...
by RWTH_FCN
Fri Mar 06, 2020 10:03 am
Forum: Vensim
Topic: Question about deleting previous runs
Replies: 4
Views: 371

Question about deleting previous runs

Hi,

I have run model several times and since dataset are huge I want to delete them. To do so, I should go in Windows->Control panel->Datasets. The problem is that I can not delet them and they stay here. Do you have any ideas why it heppens?
by RWTH_FCN
Tue Feb 04, 2020 1:27 pm
Forum: Vensim
Topic: User-defined file setup in Sensitivity Simulation - for multiple parameters
Replies: 14
Views: 885

Re: User-defined file setup in Sensitivity Simulation - for multiple parameters

I would just include the things that vary - the rest could be left in a default cin file. Then you include the sample in a sensitivity simulation via a vsc using the File method. Sounds plausible. If model takes 2 hours for run, is it possible to do stochastic optimization as well or do you just su...
by RWTH_FCN
Tue Feb 04, 2020 12:37 pm
Forum: Vensim
Topic: User-defined file setup in Sensitivity Simulation - for multiple parameters
Replies: 14
Views: 885

Re: User-defined file setup in Sensitivity Simulation - for multiple parameters

In your case, you'd have to transpose your cin file(s) into a sensitivity sample file. This isn't as hard as it sounds. If you import a cin file into Excel, and use text to columns to break things at the =, you get a column of variable names and a column of values. Do this once per file, then merge...
by RWTH_FCN
Tue Feb 04, 2020 8:42 am
Forum: Vensim
Topic: User-defined file setup in Sensitivity Simulation - for multiple parameters
Replies: 14
Views: 885

Re: User-defined file setup in Sensitivity Simulation - for multiple parameters

In Stochastic Optimization page of Manual, I encountered this sentence: "The stochastic optimization option facilitates optimization over an array of random or user-specified scenarios without first arraying the model. The total payoff is the sum of the payoffs of the individual runs in the sensitiv...
by RWTH_FCN
Mon Feb 03, 2020 3:46 pm
Forum: Vensim
Topic: User-defined file setup in Sensitivity Simulation - for multiple parameters
Replies: 14
Views: 885

Re: User-defined file setup in Sensitivity Simulation - for multiple parameters

When you say scenarios, do you mean that you have 4 files, each with a different set of variables, and you want to merge them, or ... ? Yes, I have four input files ( four CIN files). Each of them includes many variables like fuel prices, installed capacities, co2 prices, transmission constraints, ...
by RWTH_FCN
Mon Feb 03, 2020 10:53 am
Forum: Vensim
Topic: User-defined file setup in Sensitivity Simulation - for multiple parameters
Replies: 14
Views: 885

Re: User-defined file setup in Sensitivity Simulation - for multiple parameters

I see. In that case, it does seem sensible to do some kind of combinatorial resampling from the individual columns. Unfortunately, the Vensim file sensitivity isn't set up to do this, but I'll take a look - it might be simple to implement. I was also wondering how can we feed 4 scnearios simultaneo...
by RWTH_FCN
Mon Jan 27, 2020 4:05 pm
Forum: Vensim
Topic: Hearne' method
Replies: 5
Views: 755

Re: Hearne' method

It seems impractical in a large model - just too many parameters to explore. Although he has not addressed what large model means from Author's point of view, he has mentioned in the paper that "The application of this simpler method before resorting to the triangular functions might yield computat...
by RWTH_FCN
Mon Jan 27, 2020 3:55 pm
Forum: Vensim
Topic: Maximum value
Replies: 26
Views: 2545

Re: Maximum value

I think there may be a missing piece year - should min price be subscripted by year? If not, min yearly price[EndUse Region]=SUM(min price[EndUse Region]*is year[year!]) = ]=min price[EndUse Region]*SUM(is year[year!]) I have year as a subscript in the model. Anyway, I found a better solution for f...
by RWTH_FCN
Sun Jan 26, 2020 7:04 pm
Forum: Vensim
Topic: Maximum value
Replies: 26
Views: 2545

Re: Maximum value

The initial value of the input would have to be 0. It's possible that there's a 0 in the initialization step, even if the dynamic value is nonzero. Hard to say more without seeing equations and data. I cannot upload the model, but I hope these equations help to understand the problem. I want to cal...
by RWTH_FCN
Sun Jan 26, 2020 4:25 pm
Forum: Vensim
Topic: Maximum value
Replies: 26
Views: 2545

Re: Maximum value

tomfid wrote:
Sun Jan 26, 2020 4:08 pm
The initial value of the input would have to be 0. It's possible that there's a 0 in the initialization step, even if the dynamic value is nonzero. Hard to say more without seeing equations and data.
Sounds plausible. There is one 0 in initialization step. Any idea to solve it?
by RWTH_FCN
Sun Jan 26, 2020 3:35 pm
Forum: Vensim
Topic: Maximum value
Replies: 26
Views: 2545

Re: Maximum value

Administrator wrote:
Sat Jan 25, 2020 8:04 pm
Correct, that should get the minimum.
Do you have any suggestion why it always generates zero?
by RWTH_FCN
Sat Jan 25, 2020 7:18 pm
Forum: Vensim
Topic: Maximum value
Replies: 26
Views: 2545

Re: Maximum value

Administrator wrote:
Mon Jul 10, 2017 12:48 pm
This should work.

Code: Select all

MAX VALUE = SAMPLE IF TRUE ( A > MAX VALUE , A , A )
It works well for maximum. Is it correct for getting minimum?

Code: Select all

MIN VALUE = SAMPLE IF TRUE ( A <MIN VALUE , A , A )
by RWTH_FCN
Fri Jan 24, 2020 4:08 pm
Forum: Vensim
Topic: Hearne' method
Replies: 5
Views: 755

Re: Hearne' method

I assume you mean this? https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1939-7445.2009.00058.x Is it possible to use this method in an electricity market. I have a large-scale model which takes hours for one run, so I even cannot use Monte Carlo for sensitivity analysis. That's why I was wonderin...
by RWTH_FCN
Fri Jan 24, 2020 3:11 pm
Forum: Vensim
Topic: A question about calculating median
Replies: 6
Views: 442

Re: A question about calculating median

tomfid wrote:
Thu Jan 23, 2020 3:04 pm
How often do you need to update it? There might be a way to create a function to access it occasionally (e.g., monthly updates), so that the load is lower.

Is there some other robust statistic that would work?
Yearly. I want to report yearly median price of electricity for 14 regions in Europe.
by RWTH_FCN
Thu Jan 23, 2020 10:54 am
Forum: Vensim
Topic: A question about calculating median
Replies: 6
Views: 442

Re: A question about calculating median

If you're running with a 1-hr time step, this will be VERY expensive computationally, because you'll be sorting an array of 8760 values every time step. If the time step is larger, and the hour dimension is already in an array, it might work. Yes, I am running with a 1-hr time step for 35 years and...
by RWTH_FCN
Sun Jan 19, 2020 6:44 pm
Forum: Vensim
Topic: A question about calculating median
Replies: 6
Views: 442

Re: A question about calculating median

You can report the median with the Stats tool. If you need it dynamically, you store values in an array and use the VECTOR SORT-type functions to find the midpoint. I want to use second method but I get error yet. My hourly price is a stock and its flow is price change this to next hour . Can you p...
by RWTH_FCN
Tue Jan 14, 2020 6:20 pm
Forum: Vensim
Topic: A question about calculating median
Replies: 6
Views: 442

A question about calculating median

Hi, My model simulates electricty market hourly from 2015-2050 for different countries. So it produces hourly price for each year. I was wondering how can I extract median electricity price per year? My regional price for every hour is as follows: Regional Price this hour[EndUse Region]= INTEG ( pri...
by RWTH_FCN
Sat Dec 07, 2019 5:36 pm
Forum: Vensim
Topic: Integrating time step of optimization problem
Replies: 31
Views: 2907

Re: Integrating time step of optimization problem

Ah - that explains the difference. Seems like a weird way to run a market, but if those are the rules, those are the rules. Here's an idea: Suppose generators bid at cost + markup Make the markup a stock, which bidders adjust according to some pressures - e.g., maintaining a desired utilization (su...
by RWTH_FCN
Fri Dec 06, 2019 11:56 pm
Forum: Vensim
Topic: Integrating time step of optimization problem
Replies: 31
Views: 2907

Re: Integrating time step of optimization problem

Is there a reason to to have bidders bid at their own marginal cost, per theory? Its not competently marginal pricing because in discriminatory auction like pay as bid (PAB) auction bidders bid at least their cost ( it could be marginal cost or LCOE) plus a mark-up. Actually, the higher the bid, th...
by RWTH_FCN
Fri Dec 06, 2019 6:06 pm
Forum: Vensim
Topic: Integrating time step of optimization problem
Replies: 31
Views: 2907

Re: Integrating time step of optimization problem

Not sure where the original thread is, but I think the problem may be that inclusion of expected price in bid formation is not rational or competitive, hence the apparent violation of theory. Yes, its related to the expected price. Actually, there is a trade-off for bidders which they trade-off bet...
by RWTH_FCN
Fri Dec 06, 2019 4:40 pm
Forum: Vensim
Topic: Integrating time step of optimization problem
Replies: 31
Views: 2907

Re: Integrating time step of optimization problem

I've attached two models, neither of which is really right, but both in the ballpark. DEMAND AT PRICE elec 2.mdlDEMAND AT PRICE elec 1.mdl #1 implements what I originally suggested, which is that everyone bids close to MAX( marg cost, expected price ). That actually implements collusion, and the pr...
by RWTH_FCN
Wed Nov 20, 2019 4:34 pm
Forum: Vensim
Topic: sensitivity analysis (vensim)
Replies: 35
Views: 2914

Re: sensitivity analysis (vensim)

Can you increase the SAVEPER or thin out the savelist a bit? If you're getting gigabytes of output from a one or two simulations, it'll be pretty unwieldy when there are many. Sorry for late response. Actually, I used increased version of SAVEPER. For my case, as long as the model is huge (simulati...
by RWTH_FCN
Wed Oct 30, 2019 6:39 pm
Forum: Vensim
Topic: sensitivity analysis (vensim)
Replies: 35
Views: 2914

Re: sensitivity analysis (vensim)

Are you using 32 or 64 bit Vensim? If you do a run with only 1 sensitivity instance (if you can), how big is the file size increment over a non-sensitivity vdf file? I am using 32 bit now. The problem occures when I increase number of iterations. I think your assumption is correct, when size of vdf...