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Re: extractive variables to files

From: Ivan Sutoris
Subject: Re: extractive variables to files
Date: Fri, 20 Mar 2009 17:13:57 +0100

On Thu, Mar 19, 2009 at 5:44 PM, Jim Maas <address@hidden> wrote:
> Apologies for syntax questions here. I have googled and made attempts
> .... still no luck!
> Ben has helped me get an initial script to run, will list it at bottom.
> Could someone show me how to
>   1. extract the values of the variables "ca" and "out" such that I can
>      store them in a data file with their appropriate independent
>      values of "t" ?
>   2. plot the same values of "ca" and "out" vs "t"/
>   3. What does the "@" sign stand for here ...I've dug around and
>      googled both octave and matlab and can't find it!
> Thanks
> Jim

If I understand correctly what you want to do:

1. after you run your script, you have vectors "t" and "y" as output
from ode45. Then you can compute "ca" and "out" from y like this: (the
dot before slash operator means that division will be done

  ca = y ./ sz;
  out = vmax ./ (1+km ./ ca);

You could also use already defined function qaout: "[out,ca] =
qaout(t,y,vmax,km,sz)", but you would need to change "/" to "./" as
above, so that the function can accept vector y.

You can save variables to file with save command:
 save myfile.dat t ca out
will save variables t, ca, out to myfile.dat (this will use Octave's
own format - see "help save" for other formats)

2. You can plot several variables with
  plot (t, ca, 'r-', t, out, 'b-')
Strings 'r-' and 'b-' set color (red and blue) and linestyle (solid line).

3. @ is used to create anonymous function - see chapter 11 ("Functions
and script files") of Octave manual

Ivan Sutoris

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