>>>As for the quadrants, there's always checking the sign of the segments, i.e. which is positive which is negative. Going by segments, x and y are ++, -+. --, +-.
>>
>>Figured that out - took an old book (dated 1974)
>>
>>
>>But Math.Atan2( sin, cos) seems to take care of the quadrants
>
>It probably checks the sign of the parameters to do so, so you don't have to. Nice to know it does.

Even atn2() in vfp does - although the help says it doesn't