       Re: NDSolve, three 2-d order ODE, 6 initial conditions

• To: mathgroup at smc.vnet.net
• Subject: [mg115246] Re: NDSolve, three 2-d order ODE, 6 initial conditions
• From: michael partensky <partensky at gmail.com>
• Date: Tue, 4 Jan 2011 18:52:50 -0500 (EST)

```Thanks Robert, and everybody.
The issue is resolved.
Although there was indeed a typo in the third equation,
I used the  correct system (sorry for not updating the post).

Turned out that it was a bug in 7.0 (and  also a bug in  7.01 producing  a
different error message ) , that have been fixed in 8.0.

The details are described in my response to DrMajorBob

Now I have another problem, with the parametric plot in M. 8, but this
Basically, my several attempts to rescale and reorient the plot resulted in
severe errors and rebooting the computer (windows XP). I will try some
ideas implemented in Robert's solution - may be they will help.

Best
MP

On Tue, Jan 4, 2011 at 8:32 AM, Dr. Robert Kragler <kragler at hs-weingarten.de
> wrote:

>  Anbei ein Mma-Notebook (V5.2) mit der L=F6sung.
> Gru=DF  R. Kragler
>
>
> Am 03.01.2011 09:56, schrieb michael partensky:
>
> Hi, group!
>
> An attempt  to demonstrate a (restricted)  analogy between the Bloch
> (magnetic resonance) equation and the motion equation for a charged particle
> in the magnetic field leads to the following equation:
>
> ndSol[w_, w0_, w1_, x0_, y0_, z0_, v0x_, v0y_, v0z_, t1_] :==
>   NDSolve[{Cos[w t ] D[x[t], {t, 2}] + Sin[ w t] D[y[t], {t, 2}] - w Sin[w
> t] D[x[t], t] + w Cos[w t] D[y[t], t] == (w - w0) ( Sin[w t ] D[x[t], t] -
> Cos[w t] D[y[t], t]),
>     -Sin[w t] D[x[t], {t, 2}] + Cos[w t] D[y[t], {t, 2}] == (w - w0) (Cos[w
> t] D[x[t], t] + Sin[w t] D[y[t], t]) + w1 D[z[t], t],
>     D[z, {t, 2}] == w1 (Sin[w t] D[x[t], t] - Cos[w1 t] D[y[t], t]),
> (D[x[t], t] /. {t -> 0} ) == v0x, (D[y[t], t] /. {t -> 0} ) == v0y, (D[z[t],
> t] /. {t -> 0})  == v0z, x == x0, y == y0, z == z0 }, {x[t], y[t],
> z[t]}, {t, t1}];
>
>  catching  it?
> Thanks
> Michael Partenskii
>
>
>
>
>
> --
> Prof. Dr. Robert Kragler
> Hasenweg 5