gap> mat := [[0,1,0],[1,0,0],[0,0,1]]*Z(169)^0;
[ [ 0*Z(13), Z(13)^0, 0*Z(13) ], [ Z(13)^0, 0*Z(13), 0*Z(13) ],
[ 0*Z(13), 0*Z(13), Z(13)^0 ] ]
gap> phi := PolarityOfProjectiveSpace(mat,GF(169));
<polarity of PG(2, GF(13^2)), >