This brick represents the complex or real Helmholtz problem:
where \(k\) the wave number is a real or complex value. For a complex
version, a complex model has to be used (see
The function adding a Helmholtz brick to a model is:
getfem::add_Helmholtz_brick(md, mim, varname, dataexpr, region);
varname is the variable on which the Helmholtz term is added and
dataexpr is the wave number.