@montse  I figured out what to do, thanks for the help.

@Carl Love I'm afraid I don't quite understand. I am a beginner in Maple. I have three defined functions the first called s(t):=something  This I have plotted to diplay the graph from t=0 to t=1.

The second function is s2(t)=something. This shows the graph from t=1..20.

And then the third s3(t)=something, which shows the graph from t=20-21.

I am not sure what excaxtly to write when i try to combine them. To draw the graph for  the first function I write plot(s(t),t=0..1), but then I need it to cntinue with the second function. As you can tell I'm a bit of a noob at this, but thank you for your reply.