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MathGroup Archive 1996

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Re: implicit differentiation

  • Subject: [mg2883] Re: [mg2858] implicit differentiation
  • From: me at talmanl.mscd.edu (Lou Talman)
  • Date: 4 Jan 1996 03:54:30 -0600
  • Approved: usenet@wri.com
  • Distribution: local
  • Newsgroups: wri.mathgroup
  • Organization: Wolfram Research, Inc.
  • Sender: mj at wri.com

An alternative to Dave Wagner's use of Dt to implement  
implicit differentiation is to make the dependence explicit:

In[1]:=
  imp[u_, v_] := Log[v] + u v - 1

In[2]:=
  Map[D[#, x]&, imp[x, y[x]] == 0]

Out[2]=

                   y'[x]
  y[x] + x y'[x] + ----- == 0
                   y[x]

In[3]:=
  Solve[%, y'[x]]

Out[3]=

                     2
                 y[x]
  {{y'[x] -> -(----------)}}
               1 + x y[x]

--Lou Talman

-------------------------------
Begin forwarded message:

>From: marshall at CIS.Edu.HK
>Subject: [mg2858] implicit differentiation

How can I do implicit differentiation ?




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