Controller

Use this forum to post Vensim related questions.
swapple
Junior Member
Posts: 8
Joined: Tue Oct 27, 2020 6:35 am
Vensim version: PLE

Controller

There are three variables that when I change one of them, I like the two others would change, but sum of them be equals 1..
I meant sum of them must be always equals to 1.
How is it possible?
swapple
Junior Member
Posts: 8
Joined: Tue Oct 27, 2020 6:35 am
Vensim version: PLE

Re: Controller

any response?
Posts: 3827
Joined: Wed Mar 05, 2003 3:10 am

Re: Controller

Can you explain in more detail what you want to do?

It's easy to do something like

a = 0.5

b = 0.2

c = 1 - a - b

But that probably is not what you need to implement.

You can also call a, b and c weights.

a = 100
b = 100
c = 100

sum of a b and c = a + b + c

relative a = a / sum of a b and c
relative b = b / sum of a b and c
relative c = c / sum of a b and c

check = relative a + relative b + relative c (this should be = 1)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
tomfid
Posts: 3252
Joined: Wed May 24, 2006 4:54 am

Re: Controller

Also, in Venapp there's a SLIDEVARTIE control that handles this.
swapple
Junior Member
Posts: 8
Joined: Tue Oct 27, 2020 6:35 am
Vensim version: PLE

Re: Controller

Administrator wrote: Mon Feb 08, 2021 11:01 am Can you explain in more detail what you want to do?

It's easy to do something like

a = 0.5

b = 0.2

c = 1 - a - b

But that probably is not what you need to implement.

You can also call a, b and c weights.

a = 100
b = 100
c = 100

sum of a b and c = a + b + c

relative a = a / sum of a b and c
relative b = b / sum of a b and c
relative c = c / sum of a b and c

check = relative a + relative b + relative c (this should be = 1)
thx
what do you mean by check? how the model avoid being anything except 1?
swapple
Junior Member
Posts: 8
Joined: Tue Oct 27, 2020 6:35 am
Vensim version: PLE

Re: Controller

tomfid wrote: Mon Feb 08, 2021 6:20 pm Also, in Venapp there's a SLIDEVARTIE control that handles this.
what is Venapp? seems new to me
Posts: 3827
Joined: Wed Mar 05, 2003 3:10 am

Re: Controller

http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
tomfid
Posts: 3252
Joined: Wed May 24, 2006 4:54 am

Re: Controller

swapple wrote: Tue Mar 09, 2021 5:22 pm
Administrator wrote: Mon Feb 08, 2021 11:01 am
You can also call a, b and c weights.

a = 100
b = 100
c = 100

sum of a b and c = a + b + c

relative a = a / sum of a b and c
relative b = b / sum of a b and c
relative c = c / sum of a b and c

check = relative a + relative b + relative c (this should be = 1)
thx
what do you mean by check? how the model avoid being anything except 1?
"Check" is literally just a checksum to verify that things are working. You would use relative a/b/c as inputs to your model. The user would adjust the weights a/b/c.
swapple
Junior Member
Posts: 8
Joined: Tue Oct 27, 2020 6:35 am
Vensim version: PLE

Re: Controller

Administrator wrote: Tue Mar 09, 2021 6:26 pm http://www.vensim.com/documentation/venapps.html

Only in Vensim DSS.
thanks
swapple
Junior Member
Posts: 8
Joined: Tue Oct 27, 2020 6:35 am
Vensim version: PLE

Re: Controller

tomfid wrote: Thu Mar 11, 2021 5:11 pm
swapple wrote: Tue Mar 09, 2021 5:22 pm
Administrator wrote: Mon Feb 08, 2021 11:01 am
You can also call a, b and c weights.

a = 100
b = 100
c = 100

sum of a b and c = a + b + c

relative a = a / sum of a b and c
relative b = b / sum of a b and c
relative c = c / sum of a b and c

check = relative a + relative b + relative c (this should be = 1)
thx
what do you mean by check? how the model avoid being anything except 1?
"Check" is literally just a checksum to verify that things are working. You would use relative a/b/c as inputs to your model. The user would adjust the weights a/b/c.
thanks you mean we have to check it by ourselves
tomfid