Rotating polar coordinates 180 degrees

Hi all,

I have a series of polar coordinates (ranging from -180 - 180 degrees), some of these coordinates are reflected in the wrong direction (by 180 degrees) due to a sampling issue. I need to rotate these back to their correct angle but I'm not sure what the correct mathematical process is, i.e. I can't just add 180 degrees because then some values might come out greater than 180.

Any help would be fabulous!

Rod.

Answer 1

[Star Strider]

I don’t completely understand the problem, but when you say ‘reflected’, wouldn’t simply negating the angles do what you want?

F’rinstance:

theta_refl = [-180:10:180];     % ‘Reflected’ Angles
theta_true = -theta_refl;       % ‘True’ Angles

Answer 2

[David Young]

If you want to ensure that all angles are in the range -180 to 180, you can do this:

   theta_true = mod(theta_refl, 360) - 180;

which adds 180 to the angles, reversing their direction, then subtracts 360 from any that are over 180 so that they are in the required numerical range.