Doubt regarding angles of tan inverse

If I have some error in angles which is defined as:

e = psi - psi_d

psi and psi_d are assumed to be defined. If I want this angle "e" to be remain between -pi to +pi, i.e.,

-pi < e <= +pi.

How can I do this? Do i need to use atan2 ? If yes, can you plz say, how to use atan2 ?

Answer 1

[John D'Errico]

atan2 has nothing to do with it. At least not based on anything you said.

The difference between angles can exceed the range you want it to live in. So use mod instead. That is:

e = mod(e,2*pi);
e = e - 2*pi*(e > pi);

So, mod insures the angle will always live in the interval [0,2*pi]. It did that by effectively adding multiples of 2*pi. Then, if the number fell in the upper half of the interval [0,2*pi], I subtract 2*pi. The result will now always live in [-pi,pi].