[Q,G,H,R]
= assemb(model) assembles the matrices Q and H,
and the vectors G and R. Q should
be added to the system matrix and contains contributions from mixed
boundary conditions.

[Q,G,H,R]
= assemb(b,p,e) assembles
the matrices based on the boundary conditions specified in b and
the mesh data in p and e.

[Q,G,H,R]
= assemb(___,[],sdl),
for any of the previous input arguments, restricts the finite element
matrices to those that include the subdomain specified by the subdomain
labels in sdl. The empty argument is required in
this syntax for historic and compatibility reasons.

As explained in Elliptic Equations,
the finite element matrices and vectors correspond to the reduced
linear system and are the following.

Q is the integral of the q boundary
condition against the basis functions.

G is the integral of the g boundary
condition against the basis functions.

H is the Dirichlet condition matrix
representing hu = r.

R is the Dirichlet condition vector
for Hu = R.

For more information on the reduced linear system form of the
finite element matrices, see the assempdeDefinitions section, and the linear algebra
approach detailed in Systems of PDEs.