Week 4

A summary of useful weblinks:

  1. Email Dr Joan Adler with general questions.
  2. Email Dr Joan Adler with your targil solutions.
  3. Class email list.
  4. With fortran and c we will be using pgplot graphics and a listing of the different subroutines can be found on the local pgplot subroutines page.
  5. See the project information page for details about the projects.

You should try to see me about the project if you have not already done so.
I am collecting a set of commands for graphical manipulations on the commands page. These and other info below here are useful for Homeworks 2 and 3.
  1. xv (on aluf) is software to edit or change the format of graphical files and may not currently be working on all machines owing to license issues.
  2. On phelafel and phclass1-5 you can use the linux software command convert to change format (see man convert for help). You can also use it to turn a set of .png files into an animated gif, or to open an animated .gif out into .pngs. These are part of ImageMagick. See example .
  3. You can also use gimp (see man gimp for help) for editing or painting. Gimp is a very powerful tool.
  4. The display command is a good way to view .gif or .jpg files. Part of Imagemagick.
  5. xfig is another useful unix/linux paint tool.
For all of these you need to do an ssh -X to reach the machine you want to work on if you are not logged on there.
Download this week's programs before we start the class.
  • I present an example of c compilation on phelafel:
    download testc.c
    compile with cc testc.c -o testc.ex
    and run testc.ex
    On the website http://www.programmingsimplified.com/c-program-examples there are some hints on windows to LINUX c conversion.

  • Before we get to the algorithms, I will start with the ``physics'' of today's application. Chaos theory is an ``old'' topic in dynamics (old=1880) but interest in physics dates from the 1980s as computers began to be accessible. It sort of exploded with several applications. A phenomenon is chaotic when a tiny difference in initial conditions leads to a very different result. I will only cover classical chaos, quantum chaos is covered in a course given by Shmuel Fishman, who told me that if students request the course he will give it again. Examples of physical chaos include in astrophysics - the example I will cover later today, and a dripping faucet, see Yossi Weinstein's project and pendulums. There are undergrad lab experiments on the last two.

    We completed last week's topic of roots so we can start the material from Chapter 2 of Koonin, concerning the solution of ordinary differential equations. This will cover examples from the area of chaos theory, and is needed for the second question of targil 3 . See the additional material here. The programs for question 2 are on the http server. You need all the files there to compile the program, (pgplotcl ex2). The default as set up here is to show graphics on the screen. If you want to make a file for the homework you can either screen capture this with xv (or your program of choice), or interrupt the defaults, change the output parameters to an output device and get a file pgplot.ps. You can e.g. write convert pgplot.ps pgplot.jpg and you will get a jpg file.

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