# structured quadrilateral mesh in PDE Toolbox

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Natalia on 5 Jun 2014
Hello, I would like to ask if in the PDE Toolbox it is possible to generate a structured quadrilateral mesh instead of the triangular one? If so how can it be implemented in the code? My geometry is simply a rectangular of dimensions 3cm x 0.1mm and the mesh I would like to create is 0.5mm x 0.005mm. Here is a part of my code:
% Geometry description:
pderect([0 0.03 0.0001 0],'R1');
set(findobj(get(pde_fig,'Children'),'Tag','PDEEval'),'String','R1')
% Mesh generation:
setappdata(pde_fig,'refinemethod','regular');
setappdata(pde_fig,'jiggle',char('on','mean',''));
setappdata(pde_fig,'MesherVersion','preR2013a');
pdetool('initmesh')
pdetool('refine')
Thank you very much in advance, N
##### 2 CommentsShowHide 1 older comment
Alejandro Arrizabalaga on 29 Nov 2017

Bill Greene on 5 Jun 2014
There is no support for quadrilateral elements in PDE Toolbox-- either in the meshers or the computational modules. However, if you have a rectangular geometry, you can generate a regular triangular mesh using the poimesh function. This option isn't available in the pdetool GUI so you would need to define your problem using the command line interface.
Bill
Natalia on 11 Jun 2014
Thank you again for all the help Bill. The reason for defining a regular grid was to obtain the results already on such grid without using the unstructured grid and doing the transformation later.
In any case for one rectangle I defined it as:
width = 0.3; height = 0.0001;
gdmTrans = [3 4 0 width width 0 0 0 height height];
g = decsg(gdmTrans', 'S1', ('S1')');
[p,e,t]=poimesh(g,width/5e-3,height/0.005e-3);
figure; pdemesh(p,e,t);
pdeplot(p,e,t);
I have another question though, if I want to have a structure composed of two rectangles, one on top of another with the coordinates [0 width width 0 height height 2*height 2*height], what would be the best way to define the grid for such system as a whole?
Many thanks, Natalia

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