MathGroup Archive 2003

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RE: graph

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39665] RE: graph
  • From: "David Park" <djmp at earthlink.net>
  • Date: Sat, 1 Mar 2003 02:47:18 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Rodolphe,

Load

Needs["NumericalMath`SplineFit`"]

Use this statement...

Show[Graphics[{}],
    Frame -> True,
    PlotRange -> {{-10, 10}, {-10, 10}},
    GridLines -> Automatic,
    ImageSize -> 500];

except substitute the PlotRange that you want for your function. Then click
off the points for your curve and copy them.

For example, here are some points I clicked off, copied and pasted into my
notebook.

pts = {{-6.59751, -3.49975}, {-4.02183, -1.27227},
    {-1.22411, 1.38633}, {1.17394, 1.45819}, {3.572, -1.05671},
    {6.14768, -3.71532}, {8.45691, -6.37392}};

Then I created a spline function.

spline = SplineFit[pts, Cubic]
SplineFunction["Cubic", "{0., 6.}", <>]

This plots the resulting curve.

ParametricPlot[spline[u], {u, 0, 6}, Compiled -> False,
    Frame -> True,
    PlotRange -> {{-10, 10}, {-10, 10}},
    GridLines -> Automatic,
    ImageSize -> 500];

Or perhaps you don't want a spline function, but just want to connect the
points by straight lines. Then

Show[Graphics[
      {AbsolutePointSize[4],
        Point /@ pts,
        Line[pts]}],
    Frame -> True,
    PlotRange -> {{-10, 10}, {-10, 10}},
    GridLines -> Automatic,
    ImageSize -> 500];

The DrawGraphics package, at my web site, has a command DrawIndexedPoints
that plots a set of clicked off points and numbers them. You can then easily
edit the points by adding, replacing or changing existing points.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

From: Rodolphe [mailto:rodolphe_lampe at yahoo.fr]
To: mathgroup at smc.vnet.net

I want to put a graph but without function since I must trace myself the
function so I want the graduations but no functions ...
thx





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