[PD] Change a signal's pitch :: octaver

[Alexandre Quessy]

Hi,

Its been a few months since I wonder what would be the algorithm to 
write an signal's "pitch changer" in Pd. I searched the archives, but I 
cant find any message about an octaver or a pitch changer. This can be 
done easily with requencies, but what about signals ? Would it be 
possible simply using expr~ ? Maybe I need to review my maths...

Thanks!!

aalex