Re: problem writing a simple equation--urgent!!!

*To*: mathgroup at smc.vnet.net*Subject*: [mg50361] Re: [mg50359] problem writing a simple equation--urgent!!!*From*: "David Park" <djmp at earthlink.net>*Date*: Mon, 30 Aug 2004 01:34:34 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

You could use the following definition u[i_, j_] := x[i] + 2 x[j] u[2, 4] x[2] + 2 x[4] Or if you wanted to use different symbols for x... Clear[u] u[x_][i_, j_] := x[i] + 2x[j] u[y][2, 4] y[2] + 2 y[4] I would tend to use SetDelayed, :=, rather than Set, =, for these definitions. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: aysegul [mailto:erkenays at yahoo.com] To: mathgroup at smc.vnet.net Hi all, I have a problem about writing an equation in mathematica. I am writing the following equation: u[x_, y_] = x + 2*y and when I write for example u[2,4] , it gives the result. But the problem that I have is expressing this equation with parameters. That is u[x[1], x[2]] = x[1] + 2*x[2] but when I ask u[2,4]; it gives u[2,4] result.It doesn't calculate. So, how can I write this equation? Thanks all.