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NSolve Question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg130856] NSolve Question
  • From: "Hagwood, Charles R" <charles.hagwood at nist.gov>
  • Date: Tue, 21 May 2013 00:05:13 -0400 (EDT)
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 I have a known function f[x,y] and I want to solve the differential
 equation (1)  for v[t], using NSolve

 partial [f(v[t],v'[t])/partial x +(d/dt)[partial f(v[t],v'[t])/partial y =0                (1)

 where  v'[t] = derivative of v[t] with respect to t.

 I  did a test to set up (1).  I let

 f[x_,y_]:=x^2+y^3

 v[t]:=Sin[t]

 g1[x_,y_]:=partial f(x,y)/partial x

 g2[x_,y_]:=partial f(x,y)/partial y

 g3[t_]:=g1[v[t],v'[t]]+D[g2[v[t],v'[t]],t]

 and asked Mathematica to evaluate

 g3[t]

 but,  Mathematica gives an error. Thanks for the help

 Charles





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