>>On an Android device you can obtain:
>>
>>(a) From the magnetometer: The device orientation (i.e orientation relative to N).
>>(b) From the GPS : Bearing from current location to a specified other location.
>>
>>Both of the values are returned as the number of degrees E. of North.
>>So they are in the range of +0- +180 or -1 to -179 (-180 might be possible - haven't checked)
>>
>>I want to put an arrow on the screen pointing from the current location to the specified location (in the range of 0-360)
>>What is the most efficient algorithm ?
>>
>>Actually the magnetometer reading if for Magnetic N. and the bearing is True North but I can adjust for that later (same for the device window orientation)
>>
>>I can see a few implementations on the net but I've a feeling that they could be simplified..........
>>
>>Suggestions ?
>
>Christof Wollenhaupt had a session about sensors and how to use them within VFP at SouthWestFox last month. Send me an email if you want me to send you his material.

Thx Tor - might be interesting. What type of OS / Devices was he referring to ?