       Imposing boundary condition at infinity

• To: mathgroup at smc.vnet.net
• Subject: [mg63228] Imposing boundary condition at infinity
• From: dkjk at bigpond.net.au
• Date: Mon, 19 Dec 2005 07:02:04 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Hi all,

I need to solve a differential equation whose solution has the
contraint that it tends to zero in the infinite limit. Mathematica will
not, however, allow \[Phi][Infinity]==0 as one of the contraints. Does
mathematica have another notation for dealing with this constraint?

Thanks.

James

\!\(DSolve[{\(1\/r\^2\) D[r\^2*D[Ï?[r], r],
r] == \(1\/Ïµ\) \((Ï?[r] \((\(2*ec^2*n0\)\/\(k*T\))\) +
\(27*
q\)\/\(2*Pi*
a\^3*\@\(2*Pi\)\)*
Exp[\(-\(\(9  r^2\)\/\(2  a^2\)\)\)])\), Ï? ==
\(\(3\ \@2\ \
q\ Î»\)\/Ï?\^\(3/2\) - \(\[ExponentialE]\^\(a\^2\/\(18\ Î»\^2\)\)\ q\ \
\@\(a\^2\/Î»\^2\)\ Î»\)\/Ï? + \(a\ \[ExponentialE]\^\(a\^2\/\(18\
Î»\^2\)\)\
q\ Erf[a\/\(3\ \@2\ Î»\)]\)\/
Ï?\)\/\(4\ a\ Ïµ\ Î»\), Ï?[Infinity] == 0}, Ï?, r]\)

```

• Prev by Date: Re: Cross results?
• Next by Date: Re: Cross results?
• Previous by thread: Re: Cross results?
• Next by thread: Re: Imposing boundary condition at infinity