Sure, why not? :D

Case(IfL(Input,0.5),Input+0.5,Input-0.5)

Adjust the value of the first to whatever phase you like (0.25 for 1/4 for example), and then adjust the second two to cover the proper range along the line.

WHO WANTS SOME MATHS?! I'm feeling mathy. Anyone else ever stare wistfully at the mapping formula window and wonder what could have been? Well, don't. It's totally your best friend, just a little shy and needing some google stalking to open up.

... I need sleep.