Partial Derivatives
- To: mathgroup at smc.vnet.net
- Subject: [mg7774] Partial Derivatives
- From: govinder at Lourie.und.ac.za (Kesh Govinder)
- Date: Tue, 8 Jul 1997 22:40:55 -0400
- Organization: University of Natal
- Sender: owner-wri-mathgroup at wolfram.com
Hi
Does anyone else think that the partial derivative implementation in
Mma is a little weird? I am trying to find partial derivatives of
an equation, eg y''[x] + y'[x] + x^2 ==0.
What I would like is to say something like pD[eqn,y[x]] and get back 0
while pD[eqn,y''[x]] will give me 1. Certainly D does this. However,
I also want pD[eqn,x] to give me 2x and not y'''[x] + y''[x] + 2 x.
Can anyone please suggest a way to get around this?
Note that entering the equation as y'' + y' + x^2 does not work. Here
D[eqn,y] gives me the strange result y''' + y'' which I really cannot
understand.
I would really appreciate any help.
Thanks in advance
Kesh
--
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Kesh Govinder
Dept of Maths and App Maths, University of Natal -- Durban, South Africa
Tel: (+27) 31 260 3021
Fax: (+27) 31 260 1017
Email: govinder at lourie.und.ac.za |
govinder at ph.und.ac.za |
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