I am not sure what this is even called in math terms, but here I go...

i have a range from 0 to 1

and I want to take the value of 1 and make that 0, and 0 and make that 1. and if I have .1 make it .9 and .9 make it .1

So I am not sure how to do this. And/or what it's called.

Thanks!