Re: Failure to Evaluate?

*To*: mathgroup at smc.vnet.net*Subject*: [mg49845] Re: [mg49842] Failure to Evaluate?*From*: DrBob <drbob at bigfoot.com>*Date*: Wed, 4 Aug 2004 10:46:22 -0400 (EDT)*References*: <200408030511.BAA00239@smc.vnet.net>*Reply-to*: drbob at bigfoot.com*Sender*: owner-wri-mathgroup at wolfram.com

Clear[f, g, h] f = x^2/x + 1; g = x^4 + 7; h[x_] = Evaluate[D[f, x]/ D[g, x]] h[1] 1/(4*x^3) 1/4 Clear[f, g, h] f[x_] := x^2/x + 1 g[x_] := x^4 + 7 h[x_] := Derivative[1][f][x]/ Derivative[1][g][x] h[1] 1/4 Bobby On Tue, 3 Aug 2004 01:11:14 -0400 (EDT), Scott Guthery <sguthery at mobile-mind.com> wrote: > 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 > > > -- DrBob at bigfoot.com www.eclecticdreams.net

**References**:**Failure to Evaluate?***From:*"Scott Guthery" <sguthery@mobile-mind.com>