>>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)
>
>Not perfect, you will need to add some more logic since it gives the wrong result for some extreme values. But a step in the right direction. Unfortunately I don't have the time to fix my code.
>
>Since some people defines a full circle as -180° to + 180° while others defines it as 0° - 360°, this function tries to accommodate both definitions.
>
>

>Lparameters tnAng1, tnAng2
>Local lnDirection, lnAngle
>If m.tnAng1 < 0
>   m.tnAng1 = m.tnAng1 + 360
>Endif
>If m.tnAng2 < 0
>   m.tnAng2 = m.tnAng2 + 360
>Endif
>m.tnAng1 = m.tnAng1 % 360
>m.tnAng2 = m.tnAng2 % 360
>m.lnAngle = m.tnAng1 - m.tnAng2
>if m.lnAngle < 0
>   m.lnAngle = 360 + m.lnAngle 
>Endif
>If m.lnAngle > 180
>   m.lnAngle = m.lnAngle %180 
>   m.lnDirection = -1
>Else
>   m.lnDirection = 1
>Endif
>Return m.lnDirection * m.lnAngle

>If you manage to fix my code, please show us the result,

I'll try but it looks as if you hit the same edge case problems as me :-}