Plotting points

Posted on 2008-08-08 17:56 By isabelle1986 (1)

Categories:

How do I ...? with Maple (Student)

Dear All, I'm trying to plot points generated by something called the logistic map by using the following code:

> L:=array(1..30,1..1);
   x:=0.3;
   for i from 1 to 30 do
   x:=4*x*(1-x);
   L[i,1]:=x
   od;
   print(L);

>Lpoints:=convert(L,listlist);
>plots[pointplot](Lpoints,symbol=point);

But what I get is an error message saying "Error, (in plots/pointplot) incorrect 1st argument." Any suggestions as to how to overcome this problem?

Also,with regard to the array that is generated: the initial condition, x=0.3, does not appear in the array.The first entry in the array is 0.84,which is the first iterate of the initial condition.Any suggestions as to how I can get the initial condition to be the first entry?

Thanks for any suggestions!

Isabelle

LineChart

Comment on 2008-08-08 18:30 from Joe Riel ( Maple Rating 4

1258)

A few comments. First, you should use Array rather than array, the latter is older structure. I'd probably use a table rather than an Array, just because ...

To generate a point plot you create a listlist structure of the form [[x1,y1],[x2,y2],...]. In this case, however, because the x are merely indices, it is easier to use Statistics:-LineChart, which only asks for a list (or Vector) or points:

L := table():
x:=0.3:
for i to 30 do
    x := 4*x*(1-x);
    L[i] := x
end do:
L := convert(L,'list'):
Statistics:-LineChart(L);

A nice feature of LineChart is that it plots the points and connects them. Using plots[pointplot] gives a bunch of scattered points and it is difficult to see how they are connected.

To get the initial x in the array, swap the two lines in the do loop (the last computed x is not used).

Plotting points

LineChart

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