Using special functions (bessel, gamma, etc) in parsed expressions

[richmondodufisan]

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Question

Hi,

I was wondering if there was a way to use special functions in MOOSE. I looked at the function parser documentation:

http://warp.povusers.org/FunctionParser/fparser.html#literals

and saw that it only really covers basic ones like sin/tan/etc. I was wondering if there is a way to implement gamma, bessel functions, etc without needing to use an approximation.

[GiudGiud]

Hello

I don't think they can be used in parsed expressions.
I think the solution here is to code your own object instead of relying on the parsed capabilities

[dschwen]

The function parser is quite easy to extend. This would have to be done in libmesh to get the derivatives implemented as well. If there is interest I could add bessel functions etc. However the standard library only supports a subset of those functions. What exactly do you need?