/*
2"S5- as 4 x 4 matrices over Z[i2].
Rep 2a+2b.
*/

F<i2>:=QuadraticField(-2);

G<x,y>:=MatrixGroup<4,F|[
0,1,0,0,
-1,0,0,0,
0,0,0,1,
0,0,-1,0]
,[
-1,0,-i2,0,
0,0,1,0,
-1,1,0,i2,
1+i2,0,-1+i2,1]
>;

C:=x;D:=y;