Re: Derivative via mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg13757] Re: Derivative via mathematica
- From: jpk at max.mpae.gwdg.de
- Date: Mon, 24 Aug 1998 05:07:08 -0400
- Sender: owner-wri-mathgroup at wolfram.com
> I just used mathematica for a couple of days. I am trying to compute
> the derivative under mathematica. Because the function is complicated,
> I like to break it down.
> f[t_] = (m/(1+Exp[1/t] +b)
> Here m and b are functions of t.
> If I directly use command D after insert m and b terms, a very
> complicated equaion is gerenated, which I do not want.
> What I want is if I define the values of m' and b', rewrite the f
> m' = p
> b' = q // well, I dont know how to define, this is the idea
> f[t_, m[t], b[t]] = (m/(1+Exp[1/t] +b)
will do what You want
(1 + E^t^(-1) + beta[t]) -
(1 + E^t^(-1) + beta[t])^2
> then use the command D[f[t,m[t],b[t]],t] hopeful get a equation which is
> the function of t, p and q. How to do that?
> A related question, I tried to use non-defined function In:= m[t_]
> Out= m[t_]
> In:= D[m[t],t]
> Out= m'[t]
> and expected D[f[t,m[t],b[t]],t] contains m'[t]. Is it possible?
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