3If we normalize the solutions ˜ψ(˜x) of equation (10.12) according to the relation ∫+∞ −∞ ψ˜∗(˜x)ψ˜(˜x)d˜x = 1 , we should also take √-- ψ(x) = (1∕ L )ψ˜(x ∕L) in order to be properly normalized ∫+−∞∞ ψ∗(x)ψ(x)dx = 1 .