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How I introduce a matrix form of c coefficient in PDE equation using solvepde matlab command

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Moncef
Moncef on 1 Jul 2019
Answered: Ravi Kumar on 2 Jul 2019
Hello,
please how I introduce the c coeffecient which is has a matrix form:
c = [x-y, 0; 1, x.^2]
using "specifyCoefficients" and "solvepde" matlab command?
With best regards
I try this code
%======================================
numberOfPDE = 1;
model = createpde(numberOfPDE);
r1 = [3,4,0,0,0.5*10^-6,0.5*10^-6,-160*10^-9,-1.16*10^-6,-1.16*10^-6,-160*10^-9];
r2 = [3,4,0,0,0.5*10^-6,0.5*10^-6,0,-160*10^-9,-160*10^-9,0];
gdm = [r1; r2]';
g = decsg(gdm,'R1+R2',['R1'; 'R2']');
geometryFromEdges(model,g);
C = @(location,~)[location.x-location.y,0;1,location.x.^2];
F=@(location,~)location.x;
specifyCoefficientsspecifyCoefficients(model,'m',0,'d',0,'c',C,'a',0,'f',F);
msh = generateMesh(model,'Hmax',0.02,'GeometricOrder','linear','Jiggle','on');
pdeplot(model);
[p,e,t] = meshToPet(msh);
results = solvepde(model)
%==================================================================
and I obtain the error message:
Error using formGlobalKF2D
Coefficient evaluation function, "@(location,~)[location.x-location.y,0;1,location.x.^2]", was requested to calculate
coefficients at 1 locations so should have returned a matrix with 1 columns. Instead it returned a matrix with 2 columns.

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Answers (1)

Ravi Kumar
Ravi Kumar on 2 Jul 2019
Output of c coefficient function should be a matrix or column vector of appropriate size, where the number of columns corresponds to spatial locations as provided by location.x and location.y. Try this:
C = @(location,~)[location.x-location.y; ...
ones(size(location.x));...
zeros(size(location.x));...
location.x.^2];

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