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Differential Equation Solutions

  • To: mathgroup at
  • Subject: Differential Equation Solutions
  • From: uunet!!stewart (Kris Stewart)
  • Date: Sat, 5 May 90 10:18:55 -0700

I'm a new Mathematica user.  I was hoping for a strong differential
equation solving facility in Mathematica.  I don't know whether I'm
not using it correctly yet, or what.  I started with a simple 
initial value problem, y''= -y, y(0)=0, y'(0)=1, and I expected the
solution, y(x)=sin(x).  Instead the solution was in the equivalent,
but complicated, complex exponential form still.  Is there a easy
to simplification package that I haven't found out about?  I would
like to attempt more elaborate DEs, but would solutions returned in
as straight forward a form as possible.  Please advise.  (Note, I
ran this example with Maple and got precisely the results I expected.
Did I purchase the wrong symbolic package?)

In[3]:= DSolve[{y'[x]==w[x],w'[x]==-y[x],y[0]==0,w[0]==1},{y[x],w[x]},x]

                   -I x          2 I x            -I x       2 I x
                  E     (-I + I E     )          E     (1 + E     )
Out[3]= {{y[x] -> ---------------------, w[x] -> ------------------}}
                            2                            2

Thanks, in advance, for any community help I receive.
Kris Stewart   stewart at

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