       RE: i dont understand module.

• To: mathgroup at smc.vnet.net
• Subject: [mg46546] RE: [mg46542] i dont understand module.
• From: "David Park" <djmp at earthlink.net>
• Date: Mon, 23 Feb 2004 02:15:38 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Sean,

If you have multiple statements in a Module, you have to separate them with
a ";".

Just put a ";" after the sol = ... statement and it will work.

David Park

From: sean kim [mailto:sean_incali at yahoo.com]
To: mathgroup at smc.vnet.net

hello goup.

I just don't get this. this code was posted while back by Bob Hanlon.

All i did was to flank the routine by a module. i did so to minimize
memory used. I was hoping that by keepign things local, i can minimize
the resources used in the routine.

In:=
Needs["Graphics`"];

Module[{},
sol=NDSolve[{a'[t]==-0.1` a[t] x[t], b'[t]==-0.05` b[t] y[t],
x'[t]==-0.1` a[t] x[t]+0.05` b[t] y[t],
y'[t]==0.1` a[t] x[t]-0.05` b[t] y[t],
a==1,b==1,x==1,
y==0}, {a,b,x,y},{t,0,250}][]

Plot[Evaluate[#[][t]& /@ sol],{t,0,250},
PlotStyle->Table[Hue[(k+1)/6],{k,4}], Frame->True,
Axes->False,
PlotLegend->(#[]& /@ sol), LegendPosition->{1,-.35},
]
above fails with the following error.

Plot::plnr: sol is not a machine-size real number at t = \
0.000010416666666666666`.

if i flank the module with Do loop, then I get recursion errors

In:=
Needs["Graphics`"];

Do[
Module[{},
sol=NDSolve[{a'[t]==-0.1` a[t] x[t], b'[t]==-0.05` b[t] y[t],
x'[t]==-0.1` a[t] x[t]+0.05` b[t] y[t],
y'[t]==0.1` a[t] x[t]-0.05` b[t] y[t],
a==1,b==1,
x==1,y==0}, {a,b,x,y},{t,0,250}][]

Plot[Evaluate[#[][t]& /@ sol],{t,0,250},
PlotStyle->Table[Hue[(k+1)/6],{k,4}], Frame->True,
Axes->False,
PlotLegend->(#[]& /@ sol), LegendPosition->{1,-.35},
],
{iteration, 10}]

\$RecursionLimit::reclim: Recursion depth of 256 exceeded.

what's going on here?  and how do i fix it so that i can run it
automatically?