Bessel function of arbitrary order


I am trying to use spherical Bessel function (of arbitrary order) but haven’t find a demo on this. Is there a tutorial demo available?

Thank you.

have a look into:

here we are adding special functions from the third party library SLATEC,

best, Joachim


I tried to install ngs-special-functions with the current version of ngsolve
The installation went through but it gave me a bug when I import
It says
undefined symbol: zbesj_

Hi Guosheng,

I experienced this issue once before but cannot reproduce it anymor. Try to configure/build it again sequentially (i.e. make without ‘-j’)

I got the following error:

CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
linked by target “special_functions” in directory …/ngsolve-src/ngs-special-functions/src

– Configuring incomplete, errors occurred!

Is it due to my outdated version of Ngsolve?

that works now! Thanks, Matthiash.


Could you post the complete output? Which OS are you running on?

Thank you Matthiash. I have reinstalled netgen from source and it works now!


There was indeed a bug in the CMake scripts, a missing dependency of the build steps. It caused the ‘undefined symbol’ error and is now fixed.