Need a means to get arguments of a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg18444] Need a means to get arguments of a function*From*: Patrick Reany <reany at xroads.com>*Date*: Wed, 7 Jul 1999 00:11:30 -0400*Organization*: Crossroads Communications*Sender*: owner-wri-mathgroup at wolfram.com

I'm using version 3.0.1 to demonstrate the differentiation of composite functions. I need a means to get arguments to user-defined function(s) to demonstrate the chain rule. For example, if the user put in w = f[x,u,v] and v = h[x,y] I need to get at each of the arguments of f, even though Mathematica wants to substitute out v in f by h[x,y]. Does Mathematica allow me to get at the original number of arguments of f and does it have an indexed function that lets me get at each particular argument of f, such as allowing me to determine, say, that the third argument of f is v? Thanks Patrick