[PD] relative angle from sensor

[Peter P.]

Hi list,

I am trying to calculate the change of angles I do get from a sensor as
degrees between -180° and 180 by subtracting subsequent values.

As the jump from -180 to 180 would cause a jump here, I am wondering
what the best way to deal with these angles would be.
I am hesitating to convert the angles to angular functions such as sine,
cosine, as with them the rate of change (steepness) is not equal over
all values.

Most looking forward to hear all suggestions!

thanks, 
Peter