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Re: A Problem with x[i_]:=

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82983] Re: A Problem with x[i_]:=
  • From: Szabolcs Horvát <szhorvat at gmail.com>
  • Date: Tue, 6 Nov 2007 03:39:17 -0500 (EST)
  • References: <fgmq4o$9tv$1@smc.vnet.net>

John wrote:
> The assignment, x=N[Total[-2Log[((n)(pdpd)/v[I])^v[i]]],10], executes
> for i=1,2,..,10, and I can make a list of the 10 outcomes by repeating
> the assignment 10 times.
> 
> I thought that the assignment, x[i_]:=N{Total[-2Log[((n)(pdpd)/
> v[i])^v[i]]],10], would make a list of the 10 outcomes, without the
> necessity of manual repetitions, but Mathematica rejected it.
> 
> The error message tells me that my assignment won't execute because
> times is protected.
> 

You have to clear x, Clear[x], before you can assign to x[i_].

E.g.\ if you do
x = 2a
and then try
x[n_] = n^2
then Mathematica will interpret the second definition as (2a)[n_] = n^2, i.e.\ 
Times[2, a][n_] = n^2

To make a table with different values of a parameter, use Table.
For example, Table[n^2, {n, 1, 10}] produces a table of squares.

-- 
Szabolcs


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