How squareg works ?

I want to create a model by geometryFromEdges(model,@squareg) but i need other sizes of square. @squareg creates 1x1, but i want 0.6x0.6.

Could anybody help me understand what i need to change in squareg. I look code by using

type squareg

I know that any square is created in PDE TOOLbox and exported in workspace and i can use

geometryFromEdges(model,g)

but then i created mesh by

generateMesh(model,'Hmax',0.05,'GeometricOrder','Linear');

and that mesh is less, and even if i decrease Hmax, i get more unstable solutions of PDE in comparison if i used geometryFromEdges(model,@squareg) and then created mesh.

Answer 1

[Ravi Kumar]

Hi Pavel,

I don't fully understand your question, but I can answer a portion on how to create square of different size. You can use decsg to create geometry using coordinate information.

Here is a small example for creating square with 0.6 as edge length.

% Coordinates
lowerLeft  = [0   ,0   ];
lowerRight = [0.6 , 0  ];
upperRight = [0.6 , 0.6];
upperLeft =  [0.0 , 0.6];

% Geometry matrix
S = [3,4 lowerLeft(1), lowerRight(1), upperRight(1), upperLeft(1), ...
         lowerLeft(2), lowerRight(2), upperRight(2), upperLeft(2)];                     
gdm = S';

% Names
ns = 'S';

% Set formula 
sf = 'S';

% Invoke decsg
g = decsg(gdm,ns,sf');

% Import g into model using geometryFromEdges.
model = createpde;
geometryFromEdges(model,g);
pdegplot(model,'EdgeLabel','on');

Regards,

Ravi

[Pavel M]

Hi Ravi, thank you for your help.