>>>>General sort of question:
>>>>
>>>>I'm drawing a compass and need to determine the 'shortest' direction in which to rotate the compass (clockwise or anti-clockwise) between old and new bearings (in degrees).
>>>>In most cases it is simple but when the old and new values span the 0 degree point those solutions don't work.....
>>>>
>>>>Anyone got a foolproof algorithm (language doesn't matter - just the logic)
>>>
>>>Possibility one : move1 = the difference between oldPos and newPos gives a distance and a direction
>>>
>>>The other possibility (move2) is to take the opposite direction, where the distance is 360 - abs(move1)
>>>
>>>Take the move with the minimum absolute value
>>
>>May be being thick but I don't see how that works. Can you demonstrate with these examples:
>>
>>Old New
>>
>>350 2 (Should be clockwise)
>>10 190 (Doesn't matter)
>>20 190 (Clockwise)
>>10 350 (Anti-clockwise)
>>90 70 (Anti-clockwise)
>>5 190 (Anti-clockwise)
>>2 350 (Anti-clockwise)
>>
>>I don't care about the length of the arc - just in which direction to move.
>
>Our definition of direction differs. To me 2 to 350 is clockwise

No. Shortest distance between 2 and 350 degrees would be anti-clockwise (12 degrees) ?

>

>	? GetRotation(20, 335)
>	? GetRotation(335, 20)
>	? GetRotation(350, 2)
>	? GetRotation(20, 190)
>	? GetRotation(2, 350)
>

>
>

>function GetRotation( from, to)
>	
>	from = mod(from, 360)
>	to = mod(to, 360)
>	
>	local move1, move2, move, direction
>	
>	move1 = to - from
>	move2 = (360 - abs(move1)) * (-sign(move1 ))
>	
>	move = iif(abs(move1) < abs(move2), move1, move2)
>	direction = iif(sign(move) <=0, 'clockwise', 'counter-clockwise')
>	
>	? from, '->', to, ' degrees', abs(move), direction 
>endfunc

I'll try it.  Al's solution works though.....
>*_______________________________________________________________________________
>