How to show the resulting function hidden by Mathematica?

Question

I have
u0[r_, phi_] := Sum[I^(-n) BesselJ[n, r] Exp[I n phi], {n, -n, n}];
Limit[u0[r, phi], n -> Infinity]

but the result is not exportable to TEX, as it is hidden. How do I unhide it?
Thanks

Somos · Answer

Try the following code
fun = Sum[I^(-n) BesselJ[n, r] Exp[I n phi], {n, -k, k}];
pl = Position[fun, DifferenceRoot[_]];
fun1 = Table[{Subscript[f, i] @@ fun[[pl[[i, 1]], 0, 1, 1]] == 
   fun[[pl[[i, 1]], 0, 1, 2]]}, {i, Length@pl}] /.
    {[FormalY] -> y, [FormalN] -> n};
ReplacePart[fun, Table[pl[[i]] -> Subscript[f, i], {i, Length@pl}]]
    // TeXForm

and then
fun1 // TeXForm

where some manual editing may be needed.

How to show the resulting function hidden by Mathematica?

One Answer

Add your own answers!

Ask a Question