Great! It works! Thank you very much Best wishes David

Hello Georgios, Thanks for your reply. I've already seen your attached worksheet but it doesn't work. I'm using an older Maple Version (9.5) where the function "rept" is not available. When I copy the whole worksheet in Maple I get an error message. Therefore I'm looking for another possibility to achieve a periodic step function. Applying a Fourier-Analysis returns a sufficient approximation but needs hugh computational power because I want to superpose different step-functions and calculate the integral of this new function. Best wishes David