Re: simple Problem: D[ ]

*To*: mathgroup at smc.vnet.net*Subject*: [mg27337] Re: simple Problem: D[ ]*From*: "Paul Lutus" <nospam at nosite.com>*Date*: Wed, 21 Feb 2001 03:17:16 -0500 (EST)*References*: <96t91a$pqt@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

"Christian Maier" <maier1 at sbox.tu-graz.ac.at> wrote in message news:96t91a$pqt at smc.vnet.net... > > I use mathmatica the first time and have a problem with a deriviation: > > in a simple problem: > > f[x]=x^2 > abl=D[f[x],x] > > then Mathematica puts out f[x]' , but not 2 x > > How does it work correctly? > Thank aou in advance! You must write your function so that the "x" variable is correctly identified as being passed to the expression at the right: f[x_] := x^2 f'[x] 2 x f''[x] 2 f'''[x] 0 If you have a relatively recent version of Mathematica, look in the documentation under "1.7.1 Defining Functions" -- Paul Lutus www.arachnoid.com