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Re: Wrong partial derivatives calculated

  • To: mathgroup at smc.vnet.net
  • Subject: [mg41149] Re: Wrong partial derivatives calculated
  • From: bobhanlon at aol.com (Bob Hanlon)
  • Date: Tue, 6 May 2003 05:55:01 -0400 (EDT)
  • References: <b9514r$r86$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

xy != x y

Use explicit multiplication and you won't make this mistake.

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


Bob Hanlon

In article <b9514r$r86$1 at smc.vnet.net>, "David" <david at hushmail.com> wrote:

<< Subject:	Wrong partial derivatives calculated
From:		"David" <david at hushmail.com>
To: mathgroup at smc.vnet.net
Date:		Mon, 5 May 2003 06:42:35 +0000 (UTC)

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. >><BR><BR>


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