MathGroup Archive 1999

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Vector-valued DE's

  • To: mathgroup at smc.vnet.net
  • Subject: [mg16388] Vector-valued DE's
  • From: Dirk Kraaijpoel <kraai at geo.uu.nl>
  • Date: Thu, 11 Mar 1999 02:16:54 -0500
  • Organization: Universiteit Utrecht
  • Sender: owner-wri-mathgroup at wolfram.com

Hello out there!

I am aware that this same question has been asked here before:

* see
*
x14.dejanews.com/[ST_rn=ap]/getdoc.xp?AN=435165115&CONTEXT=920912797.927203423&hitnum=0,
*

but apparently it has not been answered. I post it again because it does
not
seem too trivial or too hard.
I would like for DSolve or NDSolve to solve a vector-valued differential
equation,
and I do not want to specify each equation separately.
Basically I want to do

NDSolve[{z'[t]==righthandside[z[t]],z[0]=incon},z,{t,0,1}]

where z[_],righthandside[_] and incon are vector-valued.
Unfortunately mathematica doesn't eat this, although it doesn't appear
to
be a fundamental problem for a function like NDSolve.

Of course I could produce tables of equations for each vector element
separately,
but that would mean that righthandside[_] would be evaluated for each
element in 
turn, which would be highly inefficient.

Does anyone know an elegant way of solving this?

Dirk Kraaijpoel


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