modifies the vector l and the matrix s such that the discretized boundary conditions dbc take effect.
additionally modifies the matrix d.
additionally modifies the matrix m.
DeployBoundaryConditions by default does not evaluate its first argument. The first argument should explicitly be a list with elements l, s, d, and m that are explicitly symbols that have assigned values corresponding to vectors and matrices. The values are modified in place according to the discretized boundary conditions so that on return from DeployBoundaryConditions, the symbols will evaluate to the new values.
The vector l and the matrices s, d, and m are system matrices and can be obtained from a DiscretizePDE object through the string property "All".