# Problem with coefficient c in function form in solving 2D-PDE (PDE toolbox)

조회 수: 2(최근 30일)
Chiara Moreschini 2020년 5월 1일
댓글: Chiara Moreschini 2020년 5월 1일
I'm trying to solve a 2D-PDE with a c coefficent in function form, but i'm having some trouble in using location struct.
here is my function for c coefficient:
______________________________________________
function cmatrix = ccoeffunction(location,~)
n1 = 4;
nr = numel(location.x);
Ds=1.4e-10;
jv=2e-5;
cmatrix = zeros(n1,nr);
cmatrix(1,:) = Ds*ones(1,nr);
cmatrix(2,:) = jv*(location.y)+jv*((location.y).^3)/3;
cmatrix(3,:) = -jv*(location.x)+Ds*((location.x)./(location.y));
cmatrix(4,:) = Ds*ones(1,nr);
end
_______________________________________________
However the location struct passed to the function contains in fields x and y just one zero, so my function doesen't work correctly.
______________________________________________
location =
struct with fields:
x: 0
y: 0
z: 0
subdomain: 1
_______________________________________________
How can i pass to my function the correct location struct???
Thanks

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### 채택된 답변

Ravi Kumar 2020년 5월 1일
Hi Chiara,
Solver will call the function several times to check if it is returing the correct format of coeff and so on, for these probing calls a single point is used. If you continue and get past this initial calls, you will be able to see that solver eventually calls with location of several Gauss points where element matrices are integrated.
Regards,
Ravi
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Chiara Moreschini 2020년 5월 1일
Thank you very much!!

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