RE: functional notation
- To: mathgroup at smc.vnet.net
- Subject: [mg26051] RE: [mg26034] functional notation
- From: "David Park" <djmp at earthlink.net>
- Date: Sat, 18 Nov 2000 23:08:05 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Jerry, I think you have to specify that x is a function of t and not just a symbol in your first statement. Why not do it this way: expr = D[f[x[t]], t] Derivative[1][f][x[t]]*Derivative[1][x][t] expr /. x -> (Function[t, a*t]) % /. f -> (1/#1 & ) a*Derivative[1][f][a*t] -(1/(a*t^2)) David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > -----Original Message----- > From: Blimbaum Jerry DLPC [mailto:BlimbaumJE at ncsc.navy.mil] To: mathgroup at smc.vnet.net > > When I type in the following 2 lines: > > > D[f[x],x]*D[x[t],t]; > > %/.{x->Function[t,at] > > I get back > > a * f ' [Function[t, at ] ] but what I want to get back is a*f ' > [t] or a*f ' [x] > > I'm trying to do something with just functional notation and I want > certain derivatives to 'stay as is' once they are computed..I've looked at > Hold,etc. and dont know how to use them or even if they are the > correct way > to go. > > > thanks....Jerry Blimbaum NSWC Panama City, Fl