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Re: Wrong partial derivatives calculated

  • To: mathgroup at smc.vnet.net
  • Subject: [mg41146] Re: Wrong partial derivatives calculated
  • From: "Brian Gladman" <fake at nowhere.org>
  • Date: Tue, 6 May 2003 05:54:12 -0400 (EDT)
  • References: <b9514r$r86$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

"David" <david at hushmail.com> wrote in message
news:b9514r$r86$1 at smc.vnet.net...
> 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.

The right forms are:

D[x^2 + x y + y^2, x]
D[x^2 + x y + y^2, y]

There must be a space between x and y in 'xy' since, without a space, the
latter is a new symbol 'xy' and not x multiplied by y as you intend.

    Brian Gladman



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