Re: system of nonlinear ODE

• To: mathgroup at smc.vnet.net
• Subject: [mg23732] Re: system of nonlinear ODE
• From: Roland Franzius <Roland.Franzius at uos.de>
• Date: Mon, 5 Jun 2000 01:09:24 -0400 (EDT)
• References: <8gv85p\$5mt@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi Ioanna
I have changed a bit the figure a bit (don't know what's meant by Pr
here )

NDSolve[{Derivative[3][f][x] + 2.4*f[x]*
Derivative[2][f][x] - 0.8*Derivative[1][f][x]**2 +
z[x] == 0, Derivative[2][z][x] +
2.4*f[x]*Derivative[1][z][x] == 0, z[0] == 0,
Derivative[1][z][0] == 0, Derivative[2][f][0] == 0,
f[0] == 0, Derivative[1][f][10] == 0}, {f[x], z[x]},
{x, 0, 10}]

NDSolve::"ndv" : "For a boundary value problem, only nth order single
linear \
ordinary differential equations is supported."

This means Mathematica NDSolve accepts only initial value problems (your
f'(10)==0 is the problem) for systems

roland

Ioanna Pappa schrieb:
>
> Hi
> I am trying to solve a system of two nonlinear ordinary differential
> equations with initial conditions.
> The system
> is
>                            f'''(x)+2.4f(x)f''(x)-0.8(f')**2+z=0
>                           z''(x)+2.4Pr[f(x)z(x)]'=0
>                  with z(0)=0, z'(0)=0, f''(0)=0, f(0)=0, f'(10)=0
> I use NDSolve end the message that gives me is:
> NDSolve::deql:
> The first argument must have both an equation and an initial condition.
> Can you help me;
> Gianna
> ipappa at mie.uth.gr

--
Roland Franzius

+++ exactly <<n>> lines of this message have value <<FALSE>> +++

```

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