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Re: Re: Creating graph with only a few data points

  • To: mathgroup at
  • Subject: [mg28945] Re: [mg28901] Re: Creating graph with only a few data points
  • From: "Mark Harder" <harderm at>
  • Date: Sat, 19 May 2001 22:28:04 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

>>> Has anybody another idea?

I don't know if these ideas will work. I don't have time to try them, but
here they are:
   1.)     The simplest solution would be to plot voltage on the y-axis, and
current on the x-axis, instead of the other way around.  You could publish
your plot as is, or maybe there is a way of rotating the plot 90degrees
before showing it. (Does anyone know how to do this?).
  2.)    Another way to plot multivalued functions like yours is to
transform them into polar form & use PolarPlot from the Graphics` package.
Hopefully, you can still then plot the function with labeled x and y axes.
  3.)   You are trying to interpolate your data with a model-free function
function.  Don't you have a physical model, in other words, a function that
gives voltage or current as a function defined with physical parameters like
resistance (dI/dV, which will be negative above the breakpoint in voltage)?
Then you could plot that function, once you have the physical parameters
that agree with your {V,I} points, which you could obtain with NonllinearFit
(somebody else mentioned NLFit in this stream).
-mark harder

-----Original Message-----
From: Oliver Tonn <nospam at>
To: mathgroup at
Subject: [mg28945] [mg28901] Re: Creating graph with only a few data points

>First of all, thanks for trying to help me.
>I'm sorry, but your solution seems not to be applicable for my problem.
>I'm afraid, but I don't know which parameters I've to use for Table and
>I know the plot command, but not in this context.
>The other problem is, that not only the y-values is up and down, also the
>x-value do so.
>For example:
>If you have the graph for a Thyristordiode, the x-axis would be the voltage
>the diode and the y-axis is the current. Until a specific voltage is
>there is nearly no current floating. After that point a current is floating
>the voltage is going down.
>Everytime I try to enter data, e.g.
({0,0},{1,0.5},{2,0.5},{3,0.5],{1,15}), I
>get an error.
>Has anybody another idea?
>Greetings Oliver
>>Hello Oliver,
>>draw your curve on squared paper and identify the coordinates {x, y} of
>>"significant points".
>>Then proceed as shown below:
>>lst = {{1, 1}, {2, 1.5}, {2.5, 2}, {3, 3}, {4, 5}, {5, 6.5}};
>>itp = Interpolation[lst, InterpolationOrder -> 3];
>>Table[itp[x], {x, 1, 5, 0.5}]
>>Plot[itp[x], {x, 1, 5}]
>>Best regards,
>>Matthias Bode
>>Sal. Oppenheim jr. & Cie. KGaA
>>Koenigsberger Strasse 29
>>D-60487 Frankfurt am Main
>>Tel.: +49(0)69 71 34 53 80
>>Mobile: +49(0)172 6 74 95 77
>>Fax: +49(0)69 71 34 6380
>>E-mail: matthias.bode at
>>-----Ursprungliche Nachricht-----
>>Von: Oliver Tonn [mailto:nospam at]
>>Gesendet: Dienstag, 15. Mai 2001 06:59
>>An: mathgroup at
>>Betreff:  data points
>>I'm a student at a school for technicians (electronic). I'm making my
>>calculations with Mathematica.
>>For a documentation I want to create a graph with the characteristic of a
>>and a transistor. I'm looking for a software, with which I only have to
>>some significant points of the graph, the scale, and the legend. Then the
>>software should create the graph.
>>Does anybody know a software which could do that, or is it possible to do
>>with Mathematica.
>>Greetings Oliver

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