creating a lattice in matlab

Try googling Sierpinski triangle and matlab.

or you could translate something like this currently in C to matlab

http://www.physics.utah.edu/~jasonu/code/sierpinski.cc

Nothing MATLAB specific but there is a section on nonorthogonal unstructured grids in Taflove
(at least the third edition).

Two things to keep in mind though
1) unstructured grids are much slower than rectangular grids (no easy looping)
2) The accuracy of triangular grids in particular is low (high numerical dispersion)