Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

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


  • Prev by Date: Re: Packaged Dynamic Problem
  • Next by Date: Re: Infinite function definitions
  • Previous by thread: Infinite function definitions
  • Next by thread: Re: Infinite function definitions