RE: Simple Differentiation?

*To*: mathgroup at smc.vnet.net*Subject*: [mg46023] RE: [mg46014] Simple Differentiation?*From*: "sabrina casagrande" <sabrinacasagrande at hotmail.com>*Date*: Tue, 3 Feb 2004 03:20:53 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

I'm not very confident with Math ematica. I'm learning now for College purpose... Anyway, I think it's a little bug in your code. Let's explain... When you define f[x_]+g[x_]^:=1, you are saying to mathematica that when it find f[x_]+g[x_], it must replace it with 1. so the derivatives of a costant is zero. I think so. If I'm wrong, let me know. ciao sabbri From: "Sunil Pinnamaneni" <PINNAMA at CIMS.NYU.EDU> To: mathgroup at smc.vnet.net To: mathgroup at smc.vnet.net Subject: [mg46023] [mg46014] Simple Differentiation? Date: Mon, 2 Feb 2004 05:21:28 -0500 (EST) 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