Re: Wrong partial derivatives calculated
- To: mathgroup at smc.vnet.net
- Subject: [mg41154] Re: [mg41131] Wrong partial derivatives calculated
- From: "Eric L. Strobel" <fyzycyst at comcast.net>
- Date: Tue, 6 May 2003 05:57:36 -0400 (EDT)
- Reply-to: fyzycyst at mailaps.org
- Sender: owner-wri-mathgroup at wolfram.com
on 05/05/03 2:40 AM, David at david at hushmail.com 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. Do you have a space between the 'x' and 'y' in the cross term? If not, you might try calculating D[x^2 + xy + y^2, xy) and see what you get... (That is, 'xy' without spaces is a variable onto itself and is NOT the product of 'x' and 'y'.) - Eric. -- Eric Strobel (fyzycyst at NOSPAM^mailaps.org) ===================================================================== The odds are greatly against you being immensely smarter than everyone else in the field. If your analysis says your terminal velocity is twice the speed of light, you may have invented warp drive, but the chances are a lot better that you've screwed up. =====================================================================