units check errors

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jie
Junior Member
Posts: 10
Joined: Mon Nov 15, 2021 7:24 am
Vensim version: PLE

units check errors

Post by jie »

Hello, I want to ask what this unit error means?The error screenshot is in the attachment
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Administrator
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Posts: 4573
Joined: Wed Mar 05, 2003 3:10 am

Re: units check errors

Post by Administrator »

Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
tomfid
Administrator
Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: units check errors

Post by tomfid »

I suspect this is due to the use of DELAY1 with numerical parameters. For example, if you use DELAY1(input, 3, 0), the 3 and 0 don't have units. If instead you use DELAY1(input, delay time, 0) the time constant is properly dimensioned. This is also essential good practice, because it exposes the delay to sensitivity analysis or other testing.
jie
Junior Member
Posts: 10
Joined: Mon Nov 15, 2021 7:24 am
Vensim version: PLE

Re: units check errors

Post by jie »

Hello, do you mean that my DELAY1 function is wrong? Is it because my unit does not define synonyms? Can you tell me how to solve this unit error in the figure?
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Administrator
Super Administrator
Posts: 4573
Joined: Wed Mar 05, 2003 3:10 am

Re: units check errors

Post by Administrator »

I'd suggest doing one of the many Vensim tutorials such as the one below. They will teach you how to define units.

http://www.public.asu.edu/~kirkwood/sysdyn/SDRes.htm
On this page you will find a really good Vensim PLE tutorial.
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
jie
Junior Member
Posts: 10
Joined: Mon Nov 15, 2021 7:24 am
Vensim version: PLE

Re: units check errors

Post by jie »

Thank you, I will take this tutorial.
tomfid
Administrator
Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: units check errors

Post by tomfid »

I'm handicapped by not knowing the language, but it looks like you have two time units going - one given by the character in the denominator in the units expressions in the error message, and "day".
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