Custom source definition

Hello friends
How can an energy distribution be defined as a source in Flair?
I read Fluka manual but I did not understand. Please send me an example in this regard

Dear Hassan,

if you want to use distributions different from the built-in Gaussian and Flat ones, then you need to use a source user routine. Please have a look at the following lecture:

If you need an energy distribution, which is not available in the source_newgen.f user routine, then you will have to code the sampling function by yourself.