FUNCTION: uf_gabrielov - Gabrielov transformation

CALLING SEQUENCE:
uf_gabrielov(q,i,j)

PARAMETERS:
q - matrix of the unit form
i,j - numbers of base elements

SYNOPSIS:

• uf_gabrielov performs the Gabrielov transformation of the unit form q from vertex i to vertex j.

EXAMPLES:

> q:=uf_init([4,[1,2],[2,3],[2,4]]);

> q:=uf_gabrielov(q,1,2);

> q:=uf_gabrielov(q,2,1);