OrderFFE( z )
OrderFFE returns the order of the element z in a finite field. The
order is the smallest positive integer i such that z^i is 1.
The order of the zero in a finite field is defined to be 0.
gap> OrderFFE( Z(16)^7 );
15
gap> OrderFFE( Z(16)^5 );
3
gap> OrderFFE( Z(27)^11 );
26
gap> OrderFFE( Z(625)^13 );
48
gap> OrderFFE( Z(211)^0 );
1
GAP 3.4.4