Re: Circles

[David Kastrup]

Werner LEMBERG <wl@gnu.org> writes:

>>> There's a lot of oldish webpages with complex Bezier curve
>>> constructions for circles.
>> 
>> Those must be approximate constructions. It is not mathematically
>> possible to construct a Bézier curve which is at the same time an
>> exact circle.
>
> Well, Metafont uses a third-order Bézier approximation to build up
> circles (from four quarter circles).  However, the Metafont book says
> that the difference to a real circle is less than 0.06%, which is thus
> imperceptible.
>
> The same holds for PostScript-based fonts.

PostScript uses second-order Béziers, so it makes little sense to cite
the mathematics of Metafont here.

-- 
David Kastrup