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MathGroup Archive 1992

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CForm and DSolve

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: CForm and DSolve
  • From: vdaele at ieper.lhs.be (Marc Van Daele)
  • Date: Tue, 29 Dec 92 09:20:08 +0100

I'm working on Mma 2.0 on a NeXT (nextstep 3.0)

Question 1:
-----------
> If I do CForm[{{1,2},{2,3}}[[1,2]]] for example,
> I get the C-code : List(List(1,2),List(2,3))[1][2]
> but which header file do I need before my compiler knows the
> function List?
> (The same holds for InterpolatingFunction)

Question 2:
-----------
> DSolve[{x'[t]=a[t] x[t]} , {x[t]}, t]
> gives something like
> {{x[t] -> Exp[Integrate[a[t],t]] C[1]}}
> which seems ok BUT
>
> DSolve[{x'[t]=a[t] x[t], y'[t]=b[t] y[t]} , {x[t],y[t]}, t]
> gives something like
> {x[t] ->  Exp[t a[t]], y[t] -> Exp[t b[t]]}
> So he does not seem to know that a[t] is function of t
Is this a bug or am I missing something ??

Marc
vdaele at ieper.lhs.be





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