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How to define a maximum value for a dependent variable?

Posted Apr 11, 2011, 11:55 a.m. EDT Battery Design, Parameters, Variables, & Functions Version 4.1 2 Replies

Ertan Agar
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I have been trying to develop a performance model for an electrochemical system.
However, I got some evaluation errors of powers or logarithms when starting
the solver. This is due to concentrations getting negative values at some
solver step. I need to assure that I do not evaluate negative values, and use a maximum concentration value for all species like max(1e-9, c).

How can I define it?

Thanks,

Ertan
2 Replies Last Post Jun 17, 2015, 1:42 a.m. EDT
Ertan Agar
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Posted: 1 decade ago Apr 12, 2011, 8:13 p.m. EDT
I have just found how to define it. If you use max(c, 1e-9) everywhere in the model instead of "c", the max function will return 1e-9 if the concetration is lower than 1e-9. Therefore, you can eliminate errors due to getting negative concentrations values at some solver step.

I have just found how to define it. If you use max(c, 1e-9) everywhere in the model instead of "c", the max function will return 1e-9 if the concetration is lower than 1e-9. Therefore, you can eliminate errors due to getting negative concentrations values at some solver step.
Adnan Brkic
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Posted: 9 years ago Jun 17, 2015, 1:42 a.m. EDT
Hi,

where have I to type in the function?

Best regards,
Adnan
Hi, where have I to type in the function? Best regards, Adnan

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