Inverse of atan2d

Hi,

Does anyone know how to do the "inverse" of this matlab command atan2d?

answer = atan2d(y,x);

I have the "answer" but I need to know what y and x are.

I am not sure what to do :(

Thanks a lot!

[Guillaume]

There is an infinity of x and y that produce the same angle. Your question is akin to asking which two numbers were used to produce a particular sum. There's an infinity of solutions.

[John D'Errico]

Sadly, I can't add a +1 to a comment. :)

You need to recognize that you can multiply x and y by any constant value, and the same answer will result. So both of these computations will produce the same value for Answer.

answer = atan2d(y,x);

answer = atan2d(2*y,2*x);

The same applies for any other constant multiplier. The conclusion is you cannot ever uniquely recover the original x and y. The best you can do is recover arbitrarily one of the many values for x and y that all lie at the same "angle".

Star showed you one way to do that.

[Kash Costello]

Thank you so much for this. I really appreciate it!

Answer 1

[Star Strider]

Try this:

y = 2;
x = 3;
answer = atan2d(y,x)
xa = cosd(answer)
ya = sind(answer)
test = atan2d(ya,xa)

[Kash Costello]

Thank you so much!!!!!!! I appreciate it so much!!!!

[Star Strider]

As always, my pleasure!