Re: Simple Differentiation?
- To: mathgroup at smc.vnet.net
- Subject: [mg46106] Re: Simple Differentiation?
- From: drbob at bigfoot.com (Bobby R. Treat)
- Date: Fri, 6 Feb 2004 04:15:30 -0500 (EST)
- References: <firstname.lastname@example.org>
- Sender: owner-wri-mathgroup at wolfram.com
I'd do it this way: f[x_] := 1 - g[x] D[f[x] + g[x], x] D[f[x], x] + D[g[x], x] 0 0 Bobby "Sunil Pinnamaneni" <pinnama at cims.nyu.edu> wrote in message news:<bvla84$8r$1 at smc.vnet.net>... > In Mathematica 5.0, if one types in: > > f[x_]+g[x_]^:=1 (1) > > and then types > > dx(f[x]+g[x]) > > we get 0. > > However, if we type dx(f[x]) + dx(g[x]) after typing (1), we get > > f'[x] + g'[x]. > > Mathematica doesn't recognize that f'[x]+g'[x]= > dx(f[x]+g[x]), which equals 0. How does one get Mathematica to do this? > > I'm interested in more complicated examples, which involve more complex > differential relations, but I should be able to do things in those > situations given a nice, natural way of handling this toy case. Though this > seems like a pretty simple thing, I wasn't able to find any thing in the > Mathematica Book or elsewhere, which would help with this type of things. > > Thanks, > Sunil