Computer Accounts  and Netmath 
 

  If you are registered for Uhlenbeck's section of 427K, you will
  receive a computer account from your TA. These will be available
  on Wednesday, January 19 and for the next week or so.  You may access
  this account from any of the computer labs.  The large mathematics
  computer lab is in RLM 8.136    at the end of the hall.  There are
  lab proctors who can help you log in and who should be able to
  give you instructions on basic commands.  DO NOT LOSE YOUR ACCOUNT
  NUMBER.  We do not have a list of these, and if you lose it, the
  only possibility is to get a new slip from your TA and start up a
  new account.    All the software used officially in this class is
  in the program   netmath. (You are, of course, free to use other
  programs, but   we cannot guarantee help).  
 
  If you are using netmath on the department machines, follow
  instructions under A.  If you have a suitable computer, you
  may also download netmath onto this computer.  In this case, follow
  instructions under B.   Netmath was written by Professor Schelter in
  the mathematics department, and is free. This program does most
  operations that mathlab does.  It would be proper to
  credit Professor Schelter   and the program if you use netmath
  in presentations or projects. 

  I will use the graphics in overheads, your  TA's will give about five 
  or six assignments, and there will be graphs on all exams which are drawn
  using this software.  You may also find it useful for your project,
  if you choose to do one. Most students find using the computergraphics
  to illustrate actual solutions of differential equations is a great 
  help in understanding all aspects of both theory and application.
 
  A. To access the computer software which is written for this course, from
  your mathematics account ( machines are located   in  labs  on
  the 8th floor of RLM),

      login  (the lab proctors can help you with this)

      follow instructions about passwords, etc. 

      type NETMATH  and wait as a small window appears and then
      for a full sized window  to appear
      click on "course material" for differential equations
      click on the topic (basic direction fields or solving ODE's
           symbolically for January).
      You can move around the program using the bar at the very right,
      and the cursor is placed where you want it by clicking
      with the mouse buttons.

      Suppose you are in the basic direction field stuff.
      You can change the computer programs in blue.  Double-clicking
      brings up a direction field.  To dismiss or change this field,
      move the cursor to the upper left.  A list of possibilities will
      come up.  You can change various things about the plot and replot.
      Click on dismiss to go back to the direction field stuff.  








  B. To access the computer from outside, you may use netscape, but it
  netmath is not interactive over the internet.  You will
  have to download the software.  The address is http://www.ma.utexas.edu/
  users/wfs/netmath/netmath.html   To get instructions for downloading,
  click on the work instructions. This site also explains very carefully what
  you need to run netmath on your machine. Unfortunately the professor
  and TA's probably cannot help you with this, but you can e-mail Dr.
  Schelter if you run into difficulties.

  Both "basic direction fields" and "solving ODE's symbolically" have sample
  examples.  The easiest way to work with the program is to modify these
  examples.  Take the basic ordinary differential equation

      dy/dt =  -1.3 y  + 3.2.

  Draw the direction fields for this equation, and have the computer sketch
  the solution which passes through y = 3 when t = O.  Now solve the
  equation symbolically using the symbolic program.  What happens to
  solutions of this equation when t goes to infinity?  Which program
  is better at helping you answer this question?