Re: Need a means to get arguments of a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg18514] Re: [mg18444] Need a means to get arguments of a function*From*: "Andrzej Kozlowski" <andrzej at tuins.ac.jp>*Date*: Thu, 8 Jul 1999 22:32:52 -0400*Sender*: owner-wri-mathgroup at wolfram.com

I think you should explain more clearly what exactly you want to do. You can get the original arguments of w in held form by using In[2]:= HeldPart[w, 3] Out[2]= Hold[v] However this may not be the most convenient approach for your purpose. If you just want to demonstrate the chain rule in this case, what's wrong with the following: In[3]:= D[f[x, u, h[x, y]], y] Out[3]= (0,1) (0,0,1) h [x, y] f [x, u, h[x, y]] and so on? -- Andrzej Kozlowski Toyama International University JAPAN http://sigma.tuins.ac.jp http://eri2.tuins.ac.jp ---------- >From: Patrick Reany <reany at xroads.com> To: mathgroup at smc.vnet.net >To: mathgroup at smc.vnet.net >Subject: [mg18514] [mg18444] Need a means to get arguments of a function >Date: Wed, Jul 7, 1999, 1:11 PM > > 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 >