Re: A question of simplification
- To: mathgroup at smc.vnet.net
- Subject: [mg21108] Re: A question of simplification
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Fri, 17 Dec 1999 01:21:07 -0500 (EST)
- References: <831hts$ddt@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"Xiong Zhenhua" <eexiong at ee.ust.hk> wrote in message news:831hts$ddt at smc.vnet.net... > In Mathematica, when using partial differentiation, we get > D[c.f[x]]=0.f[x]+c.f'[x], not c.f'[x]. So, when the equation is long, > the result will be very tedious. > How can I simply the result to c.f'[x]? I have tested Simplify and > FullSimplify. It does not work. > Please help me! Thanks! > > Green How about D[c.f[x], x] /. Dot[0, _] -> 0 c . f'[x] ? Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565