how to calculate the difference between two bearings

[Guest]

I have a calculated direction field, which I want to compare to an actual
bearing, and display the results
e.g., calculated 180 degrees, actual -90 degrees: difference is 270 degrees
(absolute) or -90 (relative)

Anyone have any experience with math like this? (used to calculate direction
of a ROV based on instrument data)

 

[Stan Brown]

Mon, 7 May 2007 14:28:01 -0700 from carmanah_bc

I have a calculated direction field, which I want to compare to an actual
bearing, and display the results
e.g., calculated 180 degrees, actual -90 degrees: difference is 270 degrees
(absolute) or -90 (relative)

If calculated is in A1 and actual is in A2, then
=abs(A1-A2)
gives the absolute difference.

Are you sure that the relative is -90 degrees? I would have thought
that actual = -90 = 270, so the difference is 270-180 = +90.

Can you post the rules for computing the relative?

 

[Guest]

Thanks, the ABS function is a good solution.

Mon, 7 May 2007 14:28:01 -0700 from carmanah_bc


If calculated is in A1 and actual is in A2, then
=abs(A1-A2)
gives the absolute difference.

Are you sure that the relative is -90 degrees? I would have thought
that actual = -90 = 270, so the difference is 270-180 = +90.

Can you post the rules for computing the relative?