Stated precisely, given any tolerance ε (by tradition, the letter ε is always used) x being sufficiently close to 0 will get f(x) within ε of 1. That condition is formally written: | Stated precisely, given any tolerance ε (by tradition, the letter ε is always used) x being sufficiently close to 0 will get f(x) within ε of 1. That condition is formally written: |