[GAP Forum] Matrix group

[Nicola SOTTOCORNOLA]

Dear Gap-forum,

I'm trying to study the 80 elements group generated by the matrices

A:=[[0,0,0,0,1],
[1,0,0,0,0],
[0,1,0,0,0],
[0,0,1,0,0],
[0,0,0,1,0]];;

and

R:=[[1,0,0,0,0],
[0,1,0,0,0],
[0,0,1,0,0],
[0,0,0,-1,0],
[0,0,0,0,-1]];;

This group has a normal subgroup H of size 16.

H:=MaximalNormalSubgroups(G);                                                       
[ <group of 5x5 matrices of size 16 in characteristic 0> ]

I'd like to study the structure of H. Why I obtain the following error msg?

gap> P := PresentationViaCosetTable(H);;
Error, first argument must be a group called from
<function>( <arguments> ) called from read-eval-loop
Entering break read-eval-print loop ...
you can 'quit;' to quit to outer loop, or
you can 'return;' to continue
brk> 

Thanks, Nicola