RE: Total Derivative
- To: mathgroup at smc.vnet.net
- Subject: [mg42089] RE: [mg42088] Total Derivative
- From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>
- Date: Thu, 19 Jun 2003 03:58:47 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
>-----Original Message----- >From: Joel storch [mailto:jstorch at earthlink.net] To: mathgroup at smc.vnet.net >Sent: Wednesday, June 18, 2003 8:11 AM >To: mathgroup at smc.vnet.net >Subject: [mg42089] [mg42088] Total Derivative > > >Dt[x y,x,y] gives 1+dx/dy dy/dx > >I would expect: 1+dx/dy dy/dx + x d/dy (dy/dx) > >Can someone explain this result ? > Joel, Help says: Dt[f, x , y, ...] gives d/dx d/d y ... f Such... In[3]:= Dt[Dt[x y, y], x] Out[3]= 1 + Dt[x, y] Dt[y, x] ...as is In[1]:= Dt[x y, x, y] Out[1]= 1 + Dt[x, y] Dt[y, x] See also: In[4]:= Dt[Dt[y, x], y] Out[4]= 0 In[6]:= Dt[Dt[y, y], x] Out[6]= 0 -- Hartmut