Re: simple Problem: D[ ]

*To*: mathgroup at smc.vnet.net*Subject*: [mg27349] Re: [mg27310] simple Problem: D[ ]*From*: Tomas Garza <tgarza01 at prodigy.net.mx>*Date*: Wed, 21 Feb 2001 03:17:43 -0500 (EST)*References*: <200102200805.DAA26374@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

I see no reason why it doesn't work. In[1]:= f[x] = x^2; In[2]:= D[f[x], x] Out[2]= 2 x I suggest you define your f using the SetDelayed feature of Mathematica and a pattern as formal parameter. E.g. In[3]:= g[x_] := x^2; In[4]:= D[g[x], x] Out[4]= 2 x This way you can use your function in a more general way. For example, you cannot change the name of your variable with f, since Mathematica has no way of knowing its meaning: In[5]:= D[f[y], y] Out[5]= f'[y] whereas g can be handled normally: In[6]:= D[g[y], y] Out[6]= 2 y Tomas Garza Mexico City ----- Original Message ----- From: "Christian Maier" <maier1 at sbox.tu-graz.ac.at> To: mathgroup at smc.vnet.net Subject: [mg27349] [mg27310] simple Problem: D[ ] > > 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! > > Christian Maier > > >

**References**:**simple Problem: D[ ]***From:*Christian Maier <maier1@sbox.tu-graz.ac.at>