MATLAB: Non constant PDE toolbox coefficients with second order derivatives.

non constant aPartial Differential Equation Toolboxpde tool box

I need to specify coefficients in PDE tool box. My coefficients are related to the second derivatives not first derivatives. Can I use state.uyy and state.uxx and state.uxy as second derivatives? You can see the code here. Thank you so much.
function amatrix = acoefminsurf(region,state)
n1 = 16;
nr = numel(region.x);
amatrix = zeros(n1,nr);
normrev=-(sqrt( state.uyy(4,:).^2+state.uxx(4,:).^2-2*state.uxy(4,:).^2 ) );
amatrix(2,:) = normrev;
amatrix(7,:) = normrev;
amatrix(12,:) = normrev;

Best Answer

No, the state structure does not support uxx or uyy, as documented.
I suppose that you might try to increase the number of variables in your equation, such as making a system [u,v] and having v = ux so that uxx = vx. But I make no guarantees that you can really do this successfully. You would have to come up with coefficients and boundary conditions for the system.
Good luck,
Alan Weiss
MATLAB mathematical toolbox documentation
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