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MathGroup Archive 2002

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

  • To: mathgroup at smc.vnet.net
  • Subject: [mg32869] Re: [mg32855] Very urgent problem...PLEASE help me!
  • From: Tomas Garza <tgarza01 at prodigy.net.mx>
  • Date: Sat, 16 Feb 2002 04:35:28 -0500 (EST)
  • References: <200202150750.CAA09948@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

I usually try to stay out of homework problems, so I hope this is not the
case with you.
The solution to your system is straightforward. Try this:

In[11]:=
sol = Solve[eqn, {y1[t], y2[t], y3[t], y4[t]}]

A longish expression appears in terms of Sin[w t}, Cos[w t] and Csc[w t],
but you also have this strange Y0[2 w t] inside. The value of Y3[t] is
sol[[1, 3, 2]], which you may now plot (substitute z = w t and plot between
z = 0 and z  = 4 Pi) making Y0[2 w t] = some constant, e.g. 1. You may also
use Simplify to get a slightly simpler expression. The plot is rather ugly,
with a lot of singularities. I hope I'm interpreting your problem correctly.

Tomas Garza
Mexico City

----- Original Message -----
From: "Detlef Mueller" <Detlef.Mueller at fh-ge.de>
To: mathgroup at smc.vnet.net
Subject: [mg32869] [mg32855] Very urgent problem...PLEASE help me!


> Hi out there!
>
> I'm a student working on a test with Mathematica...and I've got
> massive problems with this task here:
>
> http://home.t-online.de/home/harrytasker/Task.nb
>
> If it's not working, here's a scan of it
>
> http://home.t-online.de/home/harrytasker/scan6.JPG
>
> (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!
>
> THANKS A LOT IN ADVANCE!
>
> Bye
> Detlef Mueller
>
> P.S.:I'm using Mathematica 3.0 on PC...if it's important.
>



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