MATLAB: Laplace equation, FEM

differencefinitelaplace equationMATLAB

Does anybody know where I could find a Matlab function which prepares the system matrix
and the right-hand side vector of the finite difference method for solving the Laplace
equation? The area is a polygon which may have concave sections. The boundary with the
Dirichlet conditions is specified. Any suggestions would be gratefully appreciated.
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