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MathGroup Archive 2002

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Re: Very urgent problem...PLEASE help me!

  • To: mathgroup at
  • Subject: [mg32863] Re: Very urgent problem...PLEASE help me!
  • From: Erk Jensen <Erk.Jensen at>
  • Date: Sat, 16 Feb 2002 04:35:20 -0500 (EST)
  • Organization: CERN
  • References: <a4iftr$9q4$>
  • Sender: owner-wri-mathgroup at

Detlef Mueller wrote:
> Hi out there!
> I'm a student working on a test with Mathematica...and I've got
> massive problems with this task here:
> If it's not working, here's a scan of it
> (Sorry it's in german..anyhow, it is obviously a system of equations.
> I just have to plot the solution of y3(t) in the limits of 0<=w t<=4
> Pi).
> But how do I do it?
> It shouldn't be that much work...but I don't get the idea HOW.
> I tried with LinearSolve...but out comes a (very complicated) result,
> which I'm not able to plot somehow.
> Also, there's this Y0-thing..nothing is specified about this, should I
> just take it as a constant (because Plot requests a numerical value!).
> So, you see, I'm rather confused...please help me!
> Bye
> Detlef Mueller
> P.S.:I'm using Mathematica 3.0 on PC...if it's important.

You have known_vector = matrix dot unknown_vector. ( ...well, I guess Y0(x) is
BesselY[0,x] ...)

So you have to do Inverse[matrix] dot known_vector to get the unknown_vector,
the 3rd component of which is your solution. You replace w t by another
variable, and plot. Since you want it logarithmic, you have to think about what
to do with negative numbers ...

All this has nothing to do with Mathematica, btw.


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