Division by 0 at time 0 not showing up

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kaetze66
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Division by 0 at time 0 not showing up

Post by kaetze66 »

Dear all

One of our students has the issue that a floating point error (division by 0 at time 0) is not happening in her model. This is a model we're using to teach SD and as far as I know every other student has been able to reproduce the floating point error.

I ran her model on my computer and the error fired. I also ran my model (with the error firing on my computer) on her computer and the error didn't fire.

She uses a mac, but other students with Macs were able to reproduce the error as well (as far as I know).

I checked the settings (Model Settings, Vensim Options) and everything seems to be in order.

Therefore I would like to know if there is a Mac Problem with that or where I should look for solving the problem.

Kind regards
Stefan
kaetze66
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Re: Division by 0 at time 0 not showing up

Post by kaetze66 »

She uses Vensim DSS, newest version
tomfid
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Re: Division by 0 at time 0 not showing up

Post by tomfid »

The Mac is, unfortunately, something of a nightmare for numerical programming. Apple's policy is to continuously churn & burn libraries and compilers, which is bad for stability. On the other hand, we've taken considerable measures to ensure exact numerical equivalence between platforms. Is the student's computer either very new or very old? What OS version is running?
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Re: Division by 0 at time 0 not showing up

Post by Administrator »

Can you post the model as well so we can take a look?

If you can also attach the Vensim settings file, that would help (it's in the user home folder, hidden and named .vensim).
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kaetze66
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Re: Division by 0 at time 0 not showing up

Post by kaetze66 »

I am checking for OS version and age of computers. I can also upload the model then. I won't be able to get the .vensim file until in three weeks when we have lecture again.
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Re: Division by 0 at time 0 not showing up

Post by Administrator »

If you can upload the model ASAP, it gives us a chance to take a look.
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Re: Division by 0 at time 0 not showing up

Post by Administrator »

One related question. If they are using DSS, are the compiling the model?

The latest version of Xcode causes floating point errors when compiling models.
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kaetze66
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Re: Division by 0 at time 0 not showing up

Post by kaetze66 »

She's has OS X Yosemite Version 10.10.5

Model is attached. Please remove the model form the post once you have had a look.

No compiling is done.

Thank you
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Re: Division by 0 at time 0 not showing up

Post by Administrator »

It all runs fine for me, the FP error is generated correctly on both Mac/Windows.

I think we'd need the .vensim file to explore any further. And let us know the exact version of Vensim being used.
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kaetze66
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Re: Division by 0 at time 0 not showing up

Post by kaetze66 »

I can't seem to find the .vensim file (tried to find it on my own computer first to give better assistance).

Could you explain what you mean by User Home Folder?

I have unhidden all files and folders and checked in my user folder (also used search) but couldn't find anything.

Thank you
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Re: Division by 0 at time 0 not showing up

Post by Administrator »

Google explains it better than I can.
https://www.google.co.uk/search?q=home+ ... 8Afoo5_gAw

I've got a note on my Mac, to display hidden files when trying to open one using the text editor, hit SHIFT-CMD-"."
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kaetze66
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Re: Division by 0 at time 0 not showing up

Post by kaetze66 »

I think we can close this topic. I haven't heard back from the student so I would assume they will use a different computer for testing.

Thank you for the help
Stefan
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