       Function of several variables

• To: mathgroup at smc.vnet.net
• Subject: [mg72077] Function of several variables
• From: "tlhiv" <thenders at gmail.com>
• Date: Mon, 11 Dec 2006 04:54:48 -0500 (EST)

```I have created a list of variables that I would like to make a function
in terms of by

M = 4;
X = Table[Subscript[x, i], {i, 1, M}]

Now I would like to make a function f that is a function of each of
these M variables.  If I were manually create this function without
taking advantage of iterators, I would do something like

f[Subscript[x,1]_,Subscript[x,2]_,Subscript[x,3]_,Subscript[x,4]_] =
1/(Subscript[x,1]+Subscript[x,2]+Subscript[x,3]+Subscript[x,4])

However, my plan is to significantly increase M, and therefore I don't
want to have to manually define f in this way.  I would like to define
it in terms of the elements of X and use the Sum in the function
definition.  In the end I'm going to be solving an optimization problem
where I try to find the "optimal" choice for these elements of X.  Can
someone offer a method for accomplishing this function definition?

Thanks,

--
Troy Henderson
Assistant Professor
Department of Mathematical Sciences