Computer Programming Workshops

• We are going to teach you computer programming for problem solving and data analysis.
• We will do it in workshops:

1	Introducing procedural programming	simple Unix and C
2	Further procedural programming	modular programming - plotting graphs
3	Introducing Maple	vocabulary, syntax,worksheets and problem solving
4	Data Analysis with IDL	signal and image processing

• The workshops are based on a sequence of tasks which you must do and complete.
• Each workshop has a script which describes the computer programming language and the tasks. The density of information in the scripts is very high. You will have to read them carefully and thoroughly.
• You can use the computer terminals to do the workshops at any time.
• You have priority for use of the terminals 9:30-12:30 on days shown in the timetable.
• Demonstrators will be on hand to help you 10:00-12:00 on days shown in the timetable.

What is UNIX?

• It is an operating system which is widely used by scientific and system programmers.
• It is designed for software development rather than just software usage.
• The interface between the user and the system is called a shell.
• The shell includes elements of procedural programming so that you can implement simple algorithms.
• Lengthy procedures can be typed into a shell script (a text file).

What is C?

• It is the most widespread procedural programming language.
• It can be used for scientific computation and systems programming.
• It is easy to translate programs from C from into other procedural languages like Fortran90.
• It is a good vehicle for teaching the principles of procedural programming.

What is Maple?

• It is a high level interactive package designed to perform symbolic mathematical calculations or computer algebra.
• It is driven using a sophisticated windows environment including high quality type setting of equations, graphs etc..
• The vocabulary and syntax provide a comprehensive language for setting up a very wide range of mathematical problems.
• It includes elements of procedural programming so that you can design and implement your own algorithms.

What is IDL?

• It is a high level interactive language designed for data display and data analysis.
• It contains a very large number of ``black boxes'' which provide easy access to complicated algorithms and procedures.
• It includes elements of procedural programming so that you can design and implement your own algorithms.

Algorithms and procedural programming

• An algorithm is a specified sequence of steps which will solve a problem.
• Procedural programming is used to implement algorithms.
• In the 1st and 2nd workshops you will learn the elements of procedural programming.
• These elements are to be found at the heart of nearly all programming languages.
• They enable you to implement algorithms to solve a very large number of problems.
• The same elements of procedural programming are present in C, Fortran, Unix Shells and Maple

The structure of an algorithm

There are usually 3 phases:

• Setting up the problem - defining variables etc.
• Performing a sequence of manipulations - decisions and repetition
• Listing or saving the answers and clearing up

Computer languages - Compilation

• The programmer types the instructions in a computer language into a text file.
• A special program called a compiler reads the file and translates the high level instructions into low level machine instructions which it writes to another file.
• The machine instructions are loaded into the computer from this file and run.
• C and Fortran 90 are compiled computer language.

In most languages the program is broken into lines or statements. There are two kinds of line or statement:

• An instruction to the compiler to help it set up the problem - this is carried out during compilation
• One step of the algorithm or procedure - this is executed at run time (when the program is run)

Computer languages - Interpretation

• The user types in a command or instruction.
• A special program called an interpeter translates the command into low level machine instructions.
• Each command is executed before the next is interpreted.
• UNIX shells and the top levels of Maple and IDL are examples of interpreted languages.

Instructions for starting the C workshops

• Log on to Windows 2000 (using CFS username and password)
• Install Exceed (if not already installed, see below)
• Start Exceed (see below)
• Log on to IRIX (owl or harrier, using IRIX username and password)

        START(click) ® Programs ® Installable Software(click) ® Central Software(click)

        General Utilities(click) ® Install Exceed v6.2 (double click)

       To start Exceed:

        START(click) ® Programs ® Exceed v6.2 ® Exceed (double click)

Instructions for starting Maple

• Log on to Windows 2000 (using CFS username and password)
• Install Maple on Windows 2000 (if not already installed, see below)
• Start Maple (see below)

        START(click) ® Programs ® Installable software(click)

        Departmental Software(double click) ® Maths and Computer Science(double click)

        Install Maple v6.02(double click)

       To start Maple from scratch:

        START(click) ® Programs ® Maple 6 ® Maple 6.02(click)

       To start a Maple worksheet:

        My Documents(double click) ® worksheet(double click)

Instructions for starting IDL

• Log on to Windows 2000 (using CFS username and password)
• Install IDL on Windows 2000 (if not already installed, see below)
• Start IDL (see below)

        START(click) ® Programs ® Installable software(click)

        Central Software(double click) ® Scientific Graphics(double click)

        Install IDL(double click)

       To start IDL:

        START(click) ® Programs ® IDL v5.4 ® IDL(click)