Re: Failure to Evaluate?
- To: mathgroup at smc.vnet.net
- Subject: [mg49859] Re: Failure to Evaluate?
- From: "Zhu Chongkai" <zhuchongkai at online.sh.cn>
- Date: Wed, 4 Aug 2004 10:46:39 -0400 (EDT)
- References: <cen8is$nt$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
What is the "D" in the defination of h? D[f, x] gives the partial derivative ?f/?x, but D[f]/D[g] means nothing. "Scott Guthery" <sguthery at mobile-mind.com> > f:=Function[#1^2/#1+1] > > g:=Function[#1^4+7] > > h:=D[f]/D[g] > > h[1] > > Gives > > ((#1^2/#1)+1 &)/(#1^4+7 &)[1] > > Why doesn't it evaluate by setting #1 to 1 to get 1/4? > > h/.#1->1//N sets #1 to 1 and gives > > (1 1 + 1 &)/(1 + 7 &) > > but still doesn't evaluate to 1/4. > > What gives? What's the Right Stuff? > > Thanks for any insight. > > Cheers, Scott >