erec :=  mu Q(n + 1) - (n + mu) Q(n) + n Q(n - 1);
with(gfun);
opoly := rectodiffeq(erec, Q(n), f(z));

Error, (in gfun:-rectodiffeq) invalid input: getname expects its 1st argument, yofz, to be of type function(name), but received (z(z)*mu(z)*_C[0](z)-mu(z)*_C[1](z)*z(z)-mu(z)*_C[0](z))/(z(z)*mu(z)-mu(z))

i find that modulo is (Im(M)+Im(N))/Im(N) but where is Im command in maple?

after tried the following package, also not correct, i guess i should use quotient and Im command

with(MTM):
with(LinearAlgebra[Modular]):

Hom := proc(M, N)
Mdim := Size(M);
M_n := Mdim[1];
M_m := Mdim[2];
Ndim := Size(N);
N_n := Ndim[1];
N_m := Ndim[2];
F := kontraHom(M,N_n);
B := kohom(N,M_m);
C := kohom(N,M_n);
D := Mod(F, B);
E := Mod(D, C);

i find a link http://en.wikipedia.org/wiki/Exponential_integral

in the link, is Ei(x) = Ei(1,x)?

is Ei(1,x) called exponential integral?

what is Ei(2,x)?

what is definition of Ei(y,x)?

readshare(gfun,analysis):
with(gfun):
orec:={y(n)+(n+1)/x*y(n+1)-y(n+2)-(n+2)/x*y(n+3)=0};
erec:=borel(orec,y(n));
edeq:=rectodiffeq(erec,y(n),Q(w));
sol := dsolve(edeq,Q(w));

i follow a book's command

with(share):
readshare(gfun,analysis):
with(gfun):
orec:={u(n+2)+u(n+1)+u(n)=n}:
odeq:=rectodiffeq(orec,u(n),y(x)):
dsolve(odeq,y(x)):
OGF:=op(2,");

orec:={(n+4)*u(n+2)+u(n+1)-(n+1)*u(n)}:
erec:=borel(orec,u(n)):
edeq:=rectodiffeq(erec,u(n),y(x)):
dsolve(edeq,y(x)):

EGF:=op(2,");

1. all can not run with dsolve in maple 15, error expecting ode or a set or list of ode,

2. what is the meaning of op(2,");?