You can of course change the domain size from 1000 units to something else, by sending a "setdomain (X)" message. However, I think you mean change the speed while keeping the domain at 1000 units... well...

The only way would be to send a float in the input of the function object that changes at the rate you want. So a line object that is set to go from 0. to 1000. at any speed you want. However then you can't use a line~ object at the output, since this method sends the Y values for every X value it receives from the left output, the list for line~ doesn't come out. Hope this helps, If you need an example patch tell me. Good luck.

V KOUPER - thank you very much for your explanation! My initial idea evolved and ended with something like this - https://youtu.be/dn7ckki6-fE :) :)