Asked by Michael
on 16 Jul 2013

In order to solve nonlinear system of pde's I need to supply, together with the pde specification, a boundary condition file or matrix:

pdenonlin(b,p,e,t,c,a,f)

where b is the Boundary condition input, p,e,t are the mesh input, and c,a,f are the coefficients.

Matlab enable us to get the boundary conditions matrix Q,G,H,R by

[Q,G,H,R]=assemb(b,p,e)

What are these matrix uses for? Are they an alternative input for pde solver? if so, how?

Thanks!

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Answer by Deepak Ramaswamy
on 19 Jul 2013

Accepted answer

Q,G,H,R are alternative ways to specify boundary conditions for assempde() (static & linear case). Typically you would use them along with the matrix representations of the PDE coefficients such as: K,M,F.

pdenonlin doesn't read the matrix form. As to why one would use the matrix form even for linear cases, they are useful in some cases. I've used them for efficiently solving 4th order PDEs, applying periodic and other global BCs and also creating state space models.

for info on how to specify "b", check out http://www.mathworks.com/help/pde/ug/boundary-conditions-for-scalar-pde.html

Deepak

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