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Re: Plot function at specific points

  • To: mathgroup at smc.vnet.net
  • Subject: [mg114122] Re: Plot function at specific points
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Wed, 24 Nov 2010 06:59:33 -0500 (EST)

You can use InterpolationOrder to control the resolution.

data == {{0, 1}, {1, 2}, {2, 3}, {3, 5},
   {4, 8}, {5, 5}, {6, 2}, {7, 1},
   {8, 1}, {9, 2}, {10, 4}};

Partition[
  Table[
   Plot[
    Interpolation[data, InterpolationOrder -> n][x],
    {x, 0, 10},
    PlotRange -> {{0, 10}, {0, 9}},
    ImageSize -> 288],
   {n, 0, 3}],
  2] // Grid

lowRes == Range[0, 10, 2];

Show[
 ListLinePlot[{#, f@#} & /@ lowRes,
  PlotStyle -> Blue],
 Plot[
  Interpolation[data, InterpolationOrder -> 1][x],
  {x, 0, 10},
  PlotStyle -> Red],
 PlotRange -> {{0, 10}, {0, 9}},
 ImageSize -> 500,
 Epilog -> {AbsolutePointSize[6], Green,
   Point[data]}]


Bob Hanlon

---- "Istv=C3=A1n Zachar" <zac at freemail.hu> wrote:

==========================
Dear Group,

is there a method to plot an InterpolatingFunction at specific pointr
WITHIN Plot? I am of course aware that I can use ListPlot at any time,
though for certain reasons I have to stick with Plot. The main reason
is that I have a large amount of InterpolatingFunctions which I plot
with Plot as default, though at request I have to plot the same
InterpolatingFunctions at different resolutions. PlotPoints and
MaxRecursion is no good here, since lower resolution has to use a
certain set of x-values, defined prior to plotting. Obviously I want
to use the same Plot setup for both high and low-resolution cases.
Below is a toy modell of the problem:

f == Interpolation[{{0, 1}, {1, 2}, {2, 3}, {3, 5}, {4, 8}, {5, 5}, {6,
2}, {7, 1}, {8, 1}, {9, 2}, {10, 4}}];
lowRes == Range[0, 10, 2];
Plot[f[x], {x, 0, 10}, PlotRange -> {{0, 10}, {0, 9}}]
ListLinePlot[{#, f@#} & /@ lowRes, PlotRange -> {{0, 10}, {0, 9}}]

Again, what I want is to have a specific Plot call instead of the
ListLinePlot, but with same result as ListLinePlot.
Note that values of 'lowRes' may not correspond the exact x-
coordinates supplied to f.

Is there a way to tell Plot explicitly the steps to use? Any idea?

Istvan


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