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[Q] Programming & "Not Floating Point Number" Error

  • To: mathgroup at smc.vnet.net
  • Subject: [mg3133] [Q] Programming & "Not Floating Point Number" Error
  • From: ntd at cs.duke.edu (Noel T. Doromal)
  • Date: Tue, 6 Feb 1996 22:49:07 -0500
  • Organization: Duke University
  • Sender: owner-wri-mathgroup at wolfram.com

Hello out there!  This is my first time on this group, so I apologize for
breaking any netiquette rules.

I have a Mma question that I hope someone out there can help me with.  I
recently started using Mma for a class and have had a hard time
"programming" with it. Here is the script/program that i wrote:

--
epsilon = .01
gamma = 7
dt = .125
stim = 0

y0 = -.5
w0 = 0.0

For[i=0, i<50, i++,
f = y0 * (1 - y0 *y0);
v = y0 + (f - w0) * dt;
w = w0 +(epsilon*(gamma*y0 - w0)) * dt;
vee[i] = v;
doubleu[i] = w;
y0 = v;
w0 = w;
]

ListPlot[{vee,doubleu}]
---

First question:  Are there examples of Mma programs out there that are
longer than a line or two?  (Or was mathematica not really made for
programming?)  I bought the book and can't find any in there.  (It
describes the control structures: do, if, for... but then gives one line
examples only)

Second: In the script above I'm essentially calculating a bunch of points
that I want to plot (V vs. W - I had to use "vee" and "doubleu" to get it
to work).  The only way I could figure to do it was to store the numbers
in a list and then use ListPlot[] but I can't get it right.  I keep
getting:

--
Graphics::gptn: 
   Coordinate vee in {1, vee} is not a floating-point number.
Graphics::gptn: 
   Coordinate doubleu in {2, doubleu} is not a floating-point number.
--

What am I doing wrong?

Thanks for the help,

Noel

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