Re: [femm] Triangulation!

[David Meeker <dmeeker@xxxxxxxxxxxxxxxxx>]

you se-ho wrote:

> To Dear All:
>
> Quick thought. triangles approximate a+bx+cy with 3 point on triangles. If
> we have sqaure or any other shape (more than 3 vertices), then we have more
> equations then needed (i.e over-determined.) Therefore, if we use square (or
> rectangles), we waste time. Can this be one of reason? Moreover, when we
> want to approximate with more than 2nd order, which is better between
> triangles with more points on them (point between vertices or center of
> traignles) and square (or triangles etc) when we can fit into shape?
>
> Any comment?
> Thanks
> Sincerely,
> Se-HO YOU

Quads aren't over-determined, The interpolation function within a quad element
has a form like:
A(x,y) = c0 + c1 x + c2 y + c3 x y
where there is a unique mapping between the four nodal values and c0,c1,c2,c3.

Dave.