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COMSOL error: Cannot evaluate expression. Undefined variable.
Posted Jan 21, 2024, 3:29 a.m. EST General, API, Modeling Tools & Definitions Version 6.2 2 Replies
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I am trying to include an external function in COMSOL. I copied the example from the manual about sin(x)/x. Compiled it into a .dll and included the library via Global Definitions > Functions > External. Then I have set function name "eval" and Arguments "x". In Plot Parameters, I have set the limits to 0 and 10. Now when I hit "Plot" I will get an error message:
Cannot evaluate expression. Undefined variable. - Variable: x - Global scope Failed to evaluate expression. - Expression: x
x is defined in Parameters with some Value. But it would make more sense to me, that x, in this case, is drawn upon the pool of the limit range.
Anyway, how do I have to set up x, so that my test plot will accept the variable and also, so that I can use the function elsewhere to evaluate?
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Hi Maximilian,
If you follow our example, you should call the function with its name, extsinc, and not the eval method. It's also worth checking that the Allow external processes setting on the Security page in the Preferences window is selected (by default, it is not selected).
Best regards,
Magnus
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Hi Maximilian,
If you follow our example, you should call the function with its name,
extsinc, and not theevalmethod. It's also worth checking that the Allow external processes setting on the Security page in the Preferences window is selected (by default, it is not selected).Best regards,
Magnus
Thank you very much. I was able to reproduce the example in the manual and now have a working solution to start with. Much appreciated!