Introduction

In this laboratory we will explore the discrete Fourier transform and the discrete convolution. While we will often work in the continuous domain in class, the only way for us to implement any of the theory is to work in the discrete domain. The software package Mathematica has a built-in command to calculate the discrete Fourier transform for arrays of any dimension. So although the user interface for the current version of Mathematica is rudimentary, we will be able to carry out the calculations that we need.

Mathematica is available on the following machines, theodora, yastrzemski, marozia, cayley, and sylvester. These are single user licenses dedicated to these machines, so you must rlogin to those machines and display the output on your local machine in order to run Mathematica. To refresh your memory:

• Find out the IP address of the machine you are currently using, the local machine, by typing telnet name_of_your_machine in a commandtool. The system will respond and tell you the IP address. For example, on my machine, marozia, it responds with 192.80.94.109 .
• On the local machine in a commandtool, enter xhost + remote_machine, which allows the machine running Mathematica to display on your machine.
• Then rlogin to one of the above remote machines using rlogin machine_name. You can then log onto that machine as usual.
• On the remote machine, do setenv DISPLAY IP_address:0.0, which will tell Mathematica to display on the local machine.
• Enter math to get Mathematica. To quit Mathematica, type Quit. Mathematica is case sensitive, so quit won't do the job.
• On the local machine in a commandtool, enter xhost -, which removes control of the local machine from the remote machine.