IsPrimitive( chi )
returns true if the irreducible character chi of the solvable group G
is not induced from any proper subgroup of G, and false otherwise.
Note that an irreducible character of a solvable group is primitive if and only if it is quasi-primitive (see TestQuasiPrimitive).
gap> IsPrimitive( Irr( Sl23 )[4] );
true
gap> IsPrimitive( Irr( Sl23 )[7] );
false
GAP 3.4.4