[GAP Forum] Decomposing rational modules

[Peter Cameron]

Dear Forum,

Is there a simple way to decompose rational permutation modules? A quick
browse of the manual suggests that one can decompose modules over finite
fields (I suppose this uses the MeatAxe) but not over the rationals
(which I naively thought would be easier).

In particular cases one can spot a vector in each submodule and then take
the sumbodule spanned by its images, but it would be nice to have something
more general...

Peter Cameron.