Create cutoff for TF1

I am trying to create a cutoff for a TF1 (f1 in my code) I created (i.e. after x = 23 I want the function to equal zero for all the remaining x values). I have included my code. If anyone has ideas on how to do this that would be greatly appreciated.

Thank you in advance,
main.cpp (2.58 KB)

Double_t y = x[0];
Double_t f = 0.0;
if (y < 23.0) f = (pi* … -y))));
return f;

That worked! Thank you so much Wile!