lists of variables

*To*: mathgroup at smc.vnet.net*Subject*: [mg58252] lists of variables*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Fri, 24 Jun 2005 03:28:42 -0400 (EDT)*Organization*: The University of Western Australia*Sender*: owner-wri-mathgroup at wolfram.com

Heath Gerhardt <heathgerhardt at hotmail.com> wrote: > I need to make lists of variables, for example > > {t1,t2,t3} > > but have not been able to figure out how to make Mathematica do this. > Tried using > > Array[t,3] > > which gives > > {t[1],t[2],t[3]} > > but then I don't know how to set the t[i]'s in expressions similar to > > F[t[1]_,t[2]_,t[3]_]:=Cos[t[1]+t[2]-t[3]] Apart from the suggestions of other respondents, there is another approach to this sort of problem. If your goal is to define a function that performs some operation on a list of variables, list operations instead. For example, defining f[x_List] := Cos[x[[1]] + x[[2]] - x[[3]]] /; Length[x]==3 Then both f[{t1, t2, t3}] and f[Array[t, {3}]] work. Indeed you can also use subscripted variables as arguments. Moreover, if your list operations treat all elements on an equal footing, then the definitions are simpler. For example, defining g[x_List] := Cos[Tr[x]] then your F is just g[t1, t2, -t3]. Cheers, Paul -- Paul Abbott Phone: +61 8 6488 2734 School of Physics, M013 Fax: +61 8 6488 1014 The University of Western Australia (CRICOS Provider No 00126G) AUSTRALIA http://physics.uwa.edu.au/~paul http://InternationalMathematicaSymposium.org/IMS2005/