Most efficient/elegant way to clip a number?

Question

Given a real (n), a maximum value this real can be (upper), and a minimum value this real can be (lower), how can we most efficiently clip n, such that it remains between lo

Answer 1

Inelegant, unsafe, costly but branchless:

n= 0.5 * (n + lower + fabs(n - lower));
n= 0.5 * (n + upper - fabs(upper - n));