in MATLAB 2015b PDE toolbox for 3D geometry, how can i specify coefficients?

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yaniv friedman
yaniv friedman 2016-11-1
编辑： Alan Weiss 2016-11-2
The 'specifyCoefficients' command is given in the documentation of the 2016b MATLAB, but in 2015b it is undefined. what should i use instead? Thank you.

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回答（1 个）

Alan Weiss
Alan Weiss 2016-11-1
编辑：Alan Weiss 2016-11-1
The R2015b documentation is here.
The specific part of the documentation dealing with coefficients is here.
To get to this documentation, I went to the MathWorks documentation page and clicked the Other Releases link on the right part of the page, just below the first divider.
You could also use the built-in documentation for your version of MATLAB, available by entering doc at the MATLAB command line, or by clicking the question mark on the upper part of the screen.
Alan Weiss
MATLAB mathematical toolbox documentation
  2 个评论
yaniv friedman
yaniv friedman 2016-11-2
Thank you.
I've looked at the documentation and still I can't figure it out. I wish to solve the London equations within my model. for that I need the coefficients to be c*laplacian(u)-b*u = 0, where c & b are constant coefficients I wish to determine, and u is the i component's equation (for 3-D).
In the PDE app for 2-D problems, its very clear and simple, yet i can't figure our the corresponding command for the 3-D model.
Thanks!
Alan Weiss
Alan Weiss 2016-11-2
编辑：Alan Weiss 2016-11-2
The equation falls into the class of problems you can solve with the c coefficient being your constant c, and the a coefficient being your constant b, and f, m, and d all = 0. Well, the problem setup is
-nabla dot (c nabla u) + au = 0,
which is the negative of your equation
c*laplacian(u) - b*u = 0.
You would call the solver as follows, after including the geometry, making a mesh, and including the boundary conditions in model:
u = assempde(model,c,a,f);
Alan Weiss
MATLAB mathematical toolbox documentation

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