Problem solving most simple elliptic PDE, 2015a

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Bananach 2016-4-13

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评论： Bananach 2016-4-13

Trying to solve $\Delta u=1$ on the unit square, I currently do

 pdem = createpde(1);
 c=1;
 a=0;
 f=1;
 geometryFromEdges(pdem,@squareg);
 generateMesh(pdem,'Hmax',0.2);
 assempde(pdem,c,a,f);

Unfortunately, the last command does not work, since it requires additionally the specification of variables P, E,T, which according to the help output specify a mesh.

Why do I need to specify the mesh again in order to solve the PDE? HOW do I specify the mesh? 'generateMesh' only gives one output.

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Answer 1

Alan Weiss 2016-4-13

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在 MATLAB Online 中打开

I do not see any error when using your set of commands, though I think the last command should be

u = assempde(pdem,c,a,f);

so you get the solution in a variable.

If you really get an error with that set of commands, please post the error that MATLAB returns.

Perhaps this example will help you understand how to solve an equation using generateMesh.

Alan Weiss

MATLAB mathematical toolbox documentation

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Bananach 2016-4-13

You are right, I am sorry. It seems that I had the variables messed up and fixed them when I created the MWE. In my defense, the output of 'help assempde' encouraged my thinking that what I wanted was not implemented since it does not list the possibility of only three inputs

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