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What's DSolve's output when it cant find a solution ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg87172] What's DSolve's output when it cant find a solution ?
  • From: zerodynamics at gmail.com
  • Date: Thu, 3 Apr 2008 05:14:40 -0500 (EST)

Im using Mathematica 6 to look for solutions to a system of nonlinear ODE's. I
don't
expect a solution, but the only output Im getting is an exact reprint
of my input.
This usually means that the arguments to the function are incorrect,
but Im
fairly certain they're OK.

Here is my input:

In[11]:=   Dsolve[{s''[t] + Cot[u[t]/2]*s'[t]*u'[t] ==  0,   u''[t] -
Sin[u[t]]*s'[t]^2 == 0 }, {s[t], u[t]}, t]
Out[11]:= Dsolve[{s''[t] + Cot[u[t]/2]*s'[t]*u'[t] ==  0,   u''[t] -
Sin[u[t]]*s'[t]^2 == 0 }, {s[t], u[t]}, t]

Is this what I should expect when DSolve can't find a solution ? Also,
this is returned immediately
without any "Running ... ".

Thanks,
Dennis


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