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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[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.


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