GPS computation question

[MarkAren]

Hi All,

Wonder if any of you can help with aproblem,

I have a pair of GPS co-ordinates and wish to derive a direction
vector from these input parameters.

Assume input format as decimal degress longitude and latitude in both
cases. Assume resulting vector 0..360.

Accuracy of result can be +- 2 degrees. Computation will be done on an
8 bit micro with 16K FLASH, 1K RAM, updates are required every couple
of seconds.

Please bear in mind that math is not one of my strong points, so
please keep answers simple if possible.

Many thanks,

Mark

[Larry Hammick]

There is a trigonometric formula for the bearing, or direction, here
for example:
http://www.pilotsweb.com/navigate/dis_dir.htm

But as for the computation, can the microchip do such things as the
inverse cosine? If not, I can probably cobble an algorithm that avoids
them. Lemme know.
LH