pgcd2(a,b):= {
  local r,u,v,r1,u1,v1,q;
    r:=a; u:=1; v:=0; r1:=b; u1:=0; v1:=1;

  while (r1!=0) {
    print (r1);
    q := iquo(r,r1);
    print(r,u,v);
    r := r1;
    u := u1;
    v:=v1;
    r1 := r-q*r1;
    u1:=u-q*u1,
    v1:=v-q*v1;
    print(r,u,v,r1,q);
    }
  return(r,u,v);
  }