PDE Tool, 2x2-matrix as coefficient 'c' in a parabolic PDE

[Benjamin Rose]

Another question which might be easy to answer for an experienced
matlab user:

I'm using the PDE Tool (Version 1.04) with Matlab 6.5R13 in order to
simulate Heat Transfer Problems. In particular, I'm trying to solve
the Heat Equation for a device including materials of anisotropic
thermal conductivity. Mathworks' User's Guide to the PDE Toolbox
explicitely mentions (see p.3-16) the possibility to insert a column
vector consisting of 2-4 elements (representing a 2x2-matrix) as
coefficient 'c' of a parabolic or an elliptic PDE ('PDE
specfications...' under 'PDE' in the GUI). Application mode is
Generic Scalar. However, trying to insert an expression like [5.5e-6;
0.5e-6] just yields the error message

Error using ==> pdetexpd
Expression evaluates to wrong size

In Expression
[5.5e-6; 0.5e-6]
When evaluating pde coefficients in subdomain 4

I also checked out other expressions (a vector with four elements or
a row vector for instance) which always led to the same error
message. I really don't have the slightest idea how to solve this
problem and I couldn't find any hint in the messages posted before.

Perhaps someone knows how to handle this...

Thanks in advance,

Ben.

[Jonathan Epperl]

Since this ancient post was my 2nd result after googleing "pdetool anisotropic," I'm posting an answer. It can be found here: http://uk.mathworks.com/help/pdf_doc/pde/pde.pdf on page 2-69.

The parameter c should be entered as
cx cy
i.e. no brackets, no nothing, for a diagonal matrix of heat conductivities just enter the two values separated by a space. Makes a loooooot of sense, doesn't it? (It doesn't, imo).