Floating point error- cant fix it, pls HELP

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ngtrang
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Posts: 18
Joined: Thu Dec 08, 2022 9:22 am
Vensim version: DSS

Floating point error- cant fix it, pls HELP

Post by ngtrang »

I have had a floating point error with the model. I tried to fix it but it doesnt work. I appear not to understand this kind of error well. Then I upload the model for your support. Please help me to fix it. Thank you.
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Administrator
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Re: Floating point error- cant fix it, pls HELP

Post by Administrator »

"Formerly collected" goes to value of approximately 2000.

"Informally collected" then goes negative which is one of the causes of the problems. Things quickly go exponential and so you get values that are too large to be stored by the computer, that causes the floating point error.

"Informally collected" has (1-"formally collected" in it's equation, that would indicate that "formally collected" should be between 0 and 1 (which it is not). This causes "Informally collected" to go negative which is one of the causes of the problems. Things quickly go exponential and so you get values that are too


I would start by fixing the unit errors as these often show up errors in equation formulation (as shown by the equation for "Informally collected").
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
ngtrang
Junior Member
Posts: 18
Joined: Thu Dec 08, 2022 9:22 am
Vensim version: DSS

Re: Floating point error- cant fix it, pls HELP

Post by ngtrang »

Administrator wrote: Sat Sep 16, 2023 8:20 pm "Formerly collected" goes to value of approximately 2000.

"Informally collected" then goes negative which is one of the causes of the problems. Things quickly go exponential and so you get values that are too large to be stored by the computer, that causes the floating point error.

"Informally collected" has (1-"formally collected" in it's equation, that would indicate that "formally collected" should be between 0 and 1 (which it is not). This causes "Informally collected" to go negative which is one of the causes of the problems. Things quickly go exponential and so you get values that are too


I would start by fixing the unit errors as these often show up errors in equation formulation (as shown by the equation for "Informally collected").
I fixed it. I am very grateful, thank you so much.
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