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Re: Wrong partial derivatives calculated

• To: mathgroup at smc.vnet.net
• Subject: [mg41187] Re: [mg41131] Wrong partial derivatives calculated
• From: "German Buitrago A." <gerbual at col2.telecom.com.co>
• Date: Tue, 6 May 2003 06:06:29 -0400 (EDT)
• References: <200305050640.CAA27865@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

David:

Although you believe that it is using single *two* variables, in fact it is
using *three*. This is due to a syntax error that consists on the absence of
a blank (or an *) among "x" and "y".

For this reason your variables are "x", "y" and "xy". (See 1.1.1 on the
Online Help).

Use:

In[1]:=
D[x^2 + x*y + y^2, x]

Out[1]=
2*x + y

In[2]:=
D[x^2 + x*y + y^2, y]

Out[2]=
x + 2*y

Germán Buitrago A.
Manizales, Colombia


----- Original Message -----
From: "David" <david at hushmail.com>
To: mathgroup at smc.vnet.net
Subject: [mg41187] [mg41131] Wrong partial derivatives calculated


> When I calculate (D[x^2 + xy + y^2, x) mathematica gives me 2y and when I
> calculate D[x^2 + xy + y^2, y) I get 2x.  These are wrong answers -- have
I
> got the syntax right?  I'm trying to find partial derivatives of x^2 + xy
+
> y^2 with respect to x and y.
>
> Thanks,
>
> David
>
>
>

• References:
  • Wrong partial derivatives calculated
    • From: "David" <david@hushmail.com>