Re: Infinite function definitions

*To*: mathgroup at smc.vnet.net*Subject*: [mg104080] Re: Infinite function definitions*From*: David Bailey <dave at removedbailey.co.uk>*Date*: Sun, 18 Oct 2009 05:23:56 -0400 (EDT)*References*: <hb709k$8rl$1@smc.vnet.net>

tzygmund mcfarlane wrote: > Hi, > > I am trying to do something basic, but am unable to. I would like to > define a sequence of functions indexed by \[DoubleStruckCapitalZ]^+. > So (pseudo-code): > > > for j in {1,2,...} > Subscript[\[Psi], j] := Subscript[f, j][x_] := 1/x^j (** something > slightly more complex than this; direct substitution below difficult > **) > end > > I then want to use the Subscript[\[Psi], j] as coefficients in further > calculations (according to the values of the parameter 'x'). So (say) > something like: > > x=10 > Sum[Subscript[\[Psi], j] y^j, {j, 1, Infinity}]/Sum[y^j, {j, 1, > Infinity}] > > Is this possible? > > Thanks. > Well, clearly if you set up the values of Subscript[\[Psi], j] in a loop, you can only create finitely many of them, so a Sum to infinity isn't going to work. Perhaps you need to explain a little more. David Bailey http://www.dbaileyconsultancy.co.uk