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Operators not Allowed in User Defined Functions
Posted Oct 9, 2023, 4:14 p.m. EDT General, Equation-Based Modeling Version 5.6 2 Replies
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I am trying to solve a multidimensional time-dependent problem in Comsol using the Coefficient Form PDE framework. My question is related to defining the initial condition, however. I would like to set:
When I try to do this using the sum() operator as described in this article, I get the error "Operators not allowed in user defined functions". My question is how else can I achieve this? Of course I know I could write this function out term-by-term but I would ideally like to take N to be quite large which makes that infeasible (or at least very tedious). Is there anyway around this?
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Since your h function appears to be a Fourier series, what is the function that it is a Fourier series for? Maybe you can use that directly as an initial condition.
Reminds me of the time I inserted a series expansion of a Bessel function, not realizing that Bessel functions were already in Comsol.
By the way- I believe your sum is over i not n??
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Mark,
an alternative may be to define a variable instead of the function. Quite a bit more complex is an external function using a DLL that needs to be coded in C.
Cheers Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com