@Carl Love 

Dear friend, this guide was very valuable to me and I learned how to write a function.
Thank you very much

@C_R 

Dear friend, this guide was very valuable to me and I learned how to write a function.
Thank you very much

@acer 

Dear friend, your advice was very valuable to me and it solved one of my biggest problems, i.e. transferring equations from Mathematica to Maple.
Thank you very much

@janhardo 

Thank you very much for taking the time to answer, but I did not understand correctly, for example, how can I write the function in the attached photo?