Re: Function of several variables

*To*: mathgroup at smc.vnet.net*Subject*: [mg72135] Re: Function of several variables*From*: dh <dh at metrohm.ch>*Date*: Wed, 13 Dec 2006 06:39:37 -0500 (EST)*References*: <eljaik$7dv$1@smc.vnet.net>

Hi Troy, in Mathematica you have the possibility to treat arguments "block-wise" instead of piecewise. Consider e.g.: fun[x__] := 1/(Plus[x]) (note the 2 underscores) here we specified that we have 1 or more arguments. We could now call fun like: fun[1],fun[1,2],fun[1,2,3] e.t.c. Daniel tlhiv wrote: > 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 > United States Military Academy > http://www.tlhiv.org >