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Re: look at this problem
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:= FullForm[D[f[x, y, z], x]] Out//FullForm= FullForm[Derivative[1, 0, 0][f][x, y, z]] In:= D[f[x, y, z], x] /. Derivative[x_, ___][_][___] -> x Out= 1 HTH, Jean-Marc P.S. I have cross-posted your query to MathGroup.