Re: Get list of function variables?

*To*: mathgroup at smc.vnet.net*Subject*: [mg83313] Re: [mg83258] Get list of function variables?*From*: DrMajorBob <drmajorbob at bigfoot.com>*Date*: Sat, 17 Nov 2007 05:24:07 -0500 (EST)*References*: <29455150.1195212238501.JavaMail.root@m35>*Reply-to*: drmajorbob at bigfoot.com

Strictly speaking, f, g, and h (a) are not functions and (b) do not have variables. In this example: f[x_,y_]:=a*x^2+b*y^2 f may act like a function, but it's actually a pattern-based rule -- and it can have several, not just the one. To find out what patterns f recognizes, you can look at DownValues@f {HoldPattern[f[x_, y_]] :> a x^2 + b y^2} Bobby On Fri, 16 Nov 2007 04:30:13 -0600, Jason Quinn <jason.lee.quinn at gmail.com> wrote: > This seems simple but how do I get the arguments to an arbitrary > function? Ideally something like getVariables[f] that just accepts the > function name as its argument. > > If I have f[x_,y_]:=a*x^2+b*y^2, getVariables[f] should return {x,y} > If I have g[n_,m_]:=a*n^2+b*m^2, getVariables[g] should return {n,m} > If I have h[w_,x_,y_,z_]:=A*w*x*y*z+B, getVariables[h] should return > {w,x,y,z} > > Thanks for any suggestions, > Jason > > -- DrMajorBob at bigfoot.com