Re: Wierdness with the laplacian
- To: mathgroup at smc.vnet.net
- Subject: [mg45153] Re: Wierdness with the laplacian
- From: "Peltio" <peltio at twilight.zone>
- Date: Thu, 18 Dec 2003 06:55:29 -0500 (EST)
- References: <brpm16$7u4$1@smc.vnet.net>
- Reply-to: "Peltio" <peltioNOSP at Miname.com.invalid>
- Sender: owner-wri-mathgroup at wolfram.com
"Peter Jay Salzman" wrote > <<Calculus`VectorAnalysis` > SetCoordinates[Spherical[r, theta, phi] > Laplacian[ Exp[r^2] ] > >Mathematica gives: > > 2 2 > r 2 r 4 >Csc[theta] (6 E r Sin[theta] + 4 E r Sin[theta]) >------------------------------------------------------ > 2 > r > >Which is wrong since Exp[r^2] is not a function of theta or phi. Nor is the function returned by Mathematica. : ) Csc is the cosecant, or the reciprocal of the Sin function. It makes the expression repent and deny its dependence on theta. Csc[x]*Sin[x] == 1 An Expand or a Simplify are the cure for your Laplacian's illness. cheers, Peltio -- Invalid address in reply-to. Crafty demunging required to mail me.