Using MATLAB at BU in MA 226

Using MATLAB at BU in MA 226
Paul Blanchard

We tend to use MATLAB and Professor John Polking's MATLAB routines dfield5 and pplane5 to make pictures of slope fields, vector fields, and phase portraits.

There are a number of ways that you can access MATLAB here at BU:

MATLAB is available on the ACS cluster. Unfortunately, ACS is currently running two versions of MATLAB, 5.0 and 5.3, and the version makes a difference to us. On ACS2, you get MATLAB 5.0, and on ACS1, ACS3, ACS4, ACS5, and ACS6 you get MATLAB 5.3. The easiest thing to do is to stick with MATLAB 5.3 (and avoid ACS2).
Also there is more than one way to access the ACS cluster, and that affects what you can do. If you are running MATLAB within the X windows environment (for example, from the big color terminals in the basement of the MCS building), then you should be able to do everything we do in class. If you are running MATLAB via some terminal program such as telnet from your dorm room or over a modem, then you probably won't be able to do the graphics. That is a big limitation, so you may find yourself working in the basement of ACS or at some other location where MATLAB is available.
There are student versions of MATLAB available at fairly decent prices, especially if you are going to use MATLAB in a number of your courses. For more information, see the web page http://www.mathworks.com/products/studentversion/index.shtml. Last time I looked, the student version of MATLAB was available in the bookstore for $100. If you have the student version of MATLAB on your personal computer, then you will need to copy the relevant .m files from ACS to an appropriate directory on your computer.

Getting started on ACS: After you log into the ACS cluster, I recommend that you make a subdirectory of your home directory for MA 226. Here's what you do (follow each line with a return):

   cd
   mkdir 226
   cd 226
   cp ~paul/226/polking5.3/* .
   ls

At this point, you should have at least 13 MATLAB .m (dot m) files in your 226 directory. Be careful about the space between the star and the dot in the cp command above. You should only need to copy these files once. I may distribute other .m files as the semester progresses, and you will have to copy those to your 226 directory. But you should be able to get started now.

Using dfield5 or pplane5 on ACS: Here are the steps that you need to follow to use dfield5 or pplane5 on a regular basis:

   cd
   cd 226
   matlab

These commands should produce a matlab session. When I did this on ACS3, here's what happened:

acs3 [226] 28) matlab

This is MATLAB V5.3. To run MATLAB V5.0, please log into
ACS2 and then run matlab.


                              < M A T L A B >
                  Copyright 1984-1999 The MathWorks, Inc.
                         Version 5.3.0.10183 (R11)
                                Jan 21 1999

 
  To get started, type one of these: helpwin, helpdesk, or demo.
  For product information, type tour or visit www.mathworks.com.
 
>>

Your UNIX prompt may look different, but that's not important. The double greater-than signs (>>) are the MATLAB prompt. Type either

dfield5

pplane5

at the MATLAB prompt. If you are running MATLAB in the X windows environment (see above), you should get what you want. If you are not in the correct environment, eventually you'll get the >> prompt back, but you won't get dfield or pplane. Here's a sequence of MATLAB commands that will confirm this for you:

   x = 0:0.1:2*pi;
   y = sin(x);
   plot(x,y)

If you don't get a window with the graph of one period of the sine function in it, then you're not in the X windows environment. Get one of your friends who knows a little about X windows to help you or try the help desk in the basement of 111 Cummington St. There is on-line help for ACS at http://www.bu.edu/computing/acs/help.

Personal computers or UNIX networks other than ACS: Much of what I have described above applies to other computers as well. But you will have to transfer the .m files from ACS to the computer or network at hand. Transfering files is best done with an "ftp" program (file transfer program). If you don't know how to use an ftp program, then you'll need help from someone. I am always glad to help get you started if you come by my office hours.

Last revision: September 3, 2000

Using MATLAB at BU in MA 226 Paul Blanchard

Using MATLAB at BU in MA 226
Paul Blanchard