Science and Computers -- PHY307/607

Homework 4

In this homework we will create a simple Java applet similar to Simple3 for plotting iterates of the Henon Map.

Login in to your SUnix account.
Type cd public_html/PHY307
Type mkdir Henon
Type cp Simple3/Simple3.java Henon/Henon.java
Type chmod 755 Henon
Type cd Henon
Type pico Henon.html
- Insert the single line < applet code=Henon.class width=300 height=300 > < /applet >
- Exit pico and save this file.
Edit Henon.java (pico Henon.java). Replace the word Simple3 in the second line with Henon.
Also, in this file change the value of xscale and yscale to 50.0.
Also, in this file replace the piece of code xscale*mymap.getX() with the code xscale*(mymap.getX()+2.0). Similarly, replace the piece of code yscale*mymap.getY() with yscale*(mymap.getY()+2.0)
Now create a new file (in the Henon directory) with the command pico Map.java.

Insert the following code into this file


public class Map{
private double x,y;
private double a,b;
Map(){
x=0.0;
y=0.0;
b=0.3;
a=1.4;
}
public void iterate(){
double xnew,ynew;
xnew=a-x*x+b*y;
ynew=x;
x=xnew;
y=ynew;
return;
}
public double getX(){
return(x);
}
public double getY(){
return(y);
}
}

Now (inside the directory Henon) compile the code by typing javac *.java. If there are no errors you should see 2 new .class files.
Type chmod 644 *.class
Type chmod 644 Henon.html
Launch Netscape and point it at web.syr.edu/~yourSUnixuserid/PHY307/ Henon/Henon.html.
Hit the iterate button - you should see the Henon attractor with b=0.3 and a=1.4.

To get credit for this homework send me the web address of your applet Henon.

This page maintained by Simon Catterall, last updated 25 October, 2000.