# [Gmsh] Lloyd smoothing broken?

Christophe Geuzaine cgeuzaine at ulg.ac.be
Wed Mar 8 20:17:32 CET 2017

```Hi Nico,

It's not a bug, it's a feature (for quad mesh generation). See http://link.springer.com/chapter/10.1007%2F978-3-642-24734-7_26 for some context.

Christophe

> On 8 Mar 2017, at 09:46, Nico Schlömer <nico.schloemer at gmail.com> wrote:
>
> Hi everyone,
>
> When using `-optimize_lloyd`, I noticed that gmsh doesn't produce centroidal tesselations but for some reason favors right angles. For the simple circle geometry
> ```
> // Points
> p1 = newp;
> Point(p1) = {0, 0, 0, 0.1};
> p2 = newp;
> Point(p2) = {1, 0, 0, 0.1};
> p3 = newp;
> Point(p3) = {0, 1, 0, 0.1};
> p4 = newp;
> Point(p4) = {-1, 0, 0, 0.1};
> p5 = newp;
> Point(p5) = {0, -1, 0, 0.1};
> // Circle arcs
> c1 = newl;
> Circle(c1) = {p2, p1, p3};
> c2 = newl;
> Circle(c2) = {p3, p1, p4};
> c3 = newl;
> Circle(c3) = {p4, p1, p5};
> c4 = newl;
> Circle(c4) = {p5, p1, p2};
> l1 = newl;
> Compound Line(l1) = {c1,c2,c3,c4};
> ll1 = newll;
> Line Loop(ll1) = {l1};
> surf1 = news;
> Plane Surface(surf1) = {ll1};
> ```
> meshed with
> ```
> gmsh -2 circle.geo -o circle.msh -optimize_lloyd 1000
> ```
> I'm getting [1] when it should really look like [2].
>
> Any hints on what might be going wrong?
>
> Cheers,
> Nico
>
> [1] http://chunk.io/f/edd6327ec586485b9c8fe7a96ba1df9a
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--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine

Free software: http://gmsh.info | http://getdp.info | http://onelab.info

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