Re: look at this problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg74074] Re: look at this problem*From*: "Jean-Marc Gulliet" <jeanmarc.gulliet at gmail.com>*Date*: Thu, 8 Mar 2007 04:42:53 -0500 (EST)*References*: <beee65f50703051217g5ea4a723s46c0d7ecca6a0176@mail.gmail.com>

On 3/5/07, Nabeel Butt <nabeel.butt at gmail.com> wrote: > > Dear Mr Jean-Marc, > I want to determine the order of a differential expression for > which i try to do: > > \!\(Plus[D[f[x, y, z], x] /. \(_\^\((x___)\)\)[___] -> x]\) > But this does not work.Any suggestions to my above code. > regards, > Nabeel Hi Nabeel, Look at the FullForm of the expression to see what pattern(s) really match what you are looking for. For instance, In[1]:= FullForm[D[f[x, y, z], x]] Out[1]//FullForm= FullForm[Derivative[1, 0, 0][f][x, y, z]] In[2]:= D[f[x, y, z], x] /. Derivative[x_, ___][_][___] -> x Out[2]= 1 HTH, Jean-Marc P.S. I have cross-posted your query to MathGroup.