Thanks for your help. Unexpectedly, his very old e-mail address still worked and he answered and agreed to change the code to C++. We had clarified still in the old days that I can use his code (that's why he had left me the *.mws files with me). The formulas we anyway had published together before.

@Preben Alsholm 

My previous answer apparently did not reach the communication.

In fact, i do not have a License. Meanwhile I found out that *.mws files can be edited, and removing some formating commands and converting manually to C give the desired result. Not elegant at all, but feasible. If someone has a better idea to convert it without a Maple license, please let me know.

Thanks all, especially Axel_Vogt. In fact I do not have a Maple License. Meanwhile I found out that *.mws files can be edited, and after removing some formatting commands, it should be it. Not elegant at all, but feasible. If anybody has a better idea, please let me know.