The deviation of a prism

A $60^\circ$ prism has $n = 1.52$. You will make the program find the deviation for every angle of incidence from $30^\circ$ to $80^\circ$, find the smallest deviation and where it happens, and check that the path is symmetric there. Then it draws the deviation against the angle of incidence.

Your tasks.

1. Inside the loop, work out dev, the deviation, from i, e and A.
2. Find least, the smallest deviation, and at, the angle of incidence where it happens.
3. Find gap, the difference between the angle of emergence and the angle of incidence at that place.