Gnuplot and Sierpinksi Triangle

问题:

Question:

I have a code, which hopefully makes a Sierpinski triangle, and I am wondering how can I output a data file that you read into gnuplot? I have never used gnuplot and I am trying to play around with it. Also, if that is not possible, how should I modify my code in order to plot my triangle so that I can see it?

Explanation of code:

I am trying to generate the Sierpinski triangle which starts at the point (0,0) and there is a 0.33 probablity that the next step will be halfway between the current point and (0,2). There is a 0.33 probability that the next step will be halfway between the current point and (1,sqrt3). There is a 0.33 probability that the next step will be halfway between the current point and (0,0).

Code:

import java.util.Random;  public class SierpinskiTriangle {     public static void main(String[] args) {         //int N = Integer.parseInt(args[0]); // number of points         int N = 5000;         double sqrt3 = Math.sqrt(3);         double x = 0.0, y = 0.0; //plots          //need to draw triangle boundary                // triangle rules         for (int i = 0; i 

回答1:

First of all, you have a couple of problems in your code:

• Integer division is leading to only the third option being considered, because 1/3 = 0 and 2/3 = 0. Use 1./3. and 2./3. instead.
• You have exchanged coordinates for the last option, x0 = 1.0; y0 = sqrt3; should be x0 = sqrt3; y0 = 1.0; instead.

Once you output the points to a file called data (I used System.out.println("" + x + " " + y); within your loop), you can do the following in gnuplot:

set size ratio -1 plot "data" u 2:1 pt 7 ps 0.3 

To monitor how the triangle gets created dot by dot you can use a loop with a pause:

set xrange [0:2] set yrange [0:1.8] do for [i=0:4999] { plot "data" u 2:1 every ::::i pt 7 ps 0.3 pause 0.1 } 

Or you can create an animated gif with a series of png files:

set term pngcairo do for [i=0:4999] { set output "".i.".png" plot "data" u 2:1 every ::::i pt 7 ps 0.3 } 

Expect the above to be slow. You can skip some of the frames to make it quicker. Then do this outside gnuplot:

convert -delay 10 -loop 0 *.png animation.gif 

For this example I used 50 points increments and changed -delay to 100:

文章来源: Gnuplot and Sierpinksi Triangle