MathGroup Archive 2003

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Wrong partial derivatives calculated

  • To: mathgroup at smc.vnet.net
  • Subject: [mg41192] Re: Wrong partial derivatives calculated
  • From: Mark Westwood <MarkCWestwood at compuserve.com>
  • Date: Tue, 6 May 2003 06:07:45 -0400 (EDT)
  • References: <b9514r$r86$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

David,

I get:

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

Out[2]=
2 x+y

In[4]:=
D[x^2+x y+y^2,y]

Out[4]=
x+2 y

I'm using v4.2.1 on Windows 95.  You might want to check:

- in your email you have included the term 'xy' which, in Mathematica's
syntax, is a symbol with the name 'xy', insert a space if you want to
indicate multiplication, as in 'x y';
- have you previously defined x and y ?  If so those definitions might
be interfering.

Regards
Mark Westwood

David wrote:
> 
> 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


  • Prev by Date: Re: differentiating evently sampled data - DFTDifferentiation.nb (1/1)
  • Next by Date: Re: Show problem, please help!
  • Previous by thread: Re: Wrong partial derivatives calculated
  • Next by thread: Re: Wrong partial derivatives calculated