       Re: matrix differential equations with NDSolve

• To: mathgroup at smc.vnet.net
• Subject: [mg40241] Re: [mg40220] matrix differential equations with NDSolve
• From: Selwyn Hollis <selwynh at earthlink.net>
• Date: Thu, 27 Mar 2003 06:50:26 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```You do need to provide DSolve and NDSolve with a list containing the
individual equations, but that can be obtained fairly easily. Here's a
simple 2x2 example.

a:= {{1, -2}, {-2, -1}};  initialvals := {1,2};

Y[t_] = Table[y[i][t], {i, Length[a]}]

{y[t], y[t]}

{y'[t] == y[t] - 2*y[t],  y'[t]
== -2*y[t] - y[t]}

{y == 1, y == 2}

ivp = Flatten[{eqns, ics}]

{y'[t] == y[t] - 2*y[t],  y'[t] ==
-2*y[t] - y[t], y == 1, y == 2}

Now you can either

DSolve[ivp, Y[t], t]

or

NDSolve[ivp, Y[t], {t, 0, 1}]

-----
Selwyn Hollis
http://www.math.armstrong.edu/faculty/hollis

On Wednesday, March 26, 2003, at 02:42  AM, Richard Easther wrote:

> Is there an easy way to solve matrix (ordinary) differential equations
> numerically inside of Mathematica? (The hard way is to spell them out
> term by term, of course)
>
> It may be I am missing something obvious, but a quick set of
> experiments with NDSolve did not bring any joy....
>
> Richard Easther
>

```

• Prev by Date: RE: List Operation ?
• Next by Date: Re: Re: DSolve and N do not commute
• Previous by thread: Re: matrix differential equations with NDSolve
• Next by thread: Re: matrix differential equations with NDSolve