       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)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
• Delivered-to: mathgroup-outx@smc.vnet.net
• Delivered-to: mathgroup-newsendx@smc.vnet.net

``` 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]

g3[t]

but,  Mathematica gives an error. Thanks for the help

Charles

```

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