Introduction -- Introduction to CIGAL

CIGAL is a general purpose interactive programming language. To use it you don't need to know anything about programming. By using only the menus and ready-made commands you have access to hundreds of useful functions. However, if you do decide to put together your own customized commands you will find that CIGAL's language features make learning to write your own programs both quick and easy. CIGAL's goal is to provide a simple interactive environment easy enough for anybody to use, while at the same time providing enough programming flexibility to permit more ambitious users to customize the system to their own needs.

CIGAL, which stands for Compilable Imaging, Graphics, and Analytical Language, was originally designed for image processing and graphical reconstruction. However, most of CIGAL's features are not restricted to image-oriented tasks. CIGAL's language can therefore be used for a wide range of data manipulation or data analysis applications.

On-Line User's Manual CIGAL's User's Manual is available online via the HELP command. The manual is designed as an interactive guide. Because the program is quite large and only parts of it are likely to be of interest at any particular time, the manual is organized into many short entries. Each entry addresses a specific topic and is just a few pages in length. You select which topic you are interested in by typing 'help' followed by the topic name. Each entry contains suggestions to look at a number of other topics providing more detailed information. These suggestions appear at the end of each entry in the form:
see SOMETHING[n] where 'SOMETHING' is the related topic and '[N]' indicates the chapter in the user manual containing that topic. For example, when 'see ACCEPT[3]' appears at the end of an entry, that means additional information relative to that topic can be found by typing 'help accept', or by looking up 'accept' in chapter 3 of the printed manual.

NOTE: When reading the HELP messages you will find that CIGAL command words are printed in capital letters. This is simply to emphasize that these words have special meaning. When you actually enter CIGAL commands, all letters are converted to lower case (unless they appear within quotation marks) so it does not matter whether you type in capital or lower case letters.

Commands CIGAL performs operations one command at a time. Commands generally take the form of a special command word, which may or may not be followed by a number of modifiers (known as command line arguments). An example of a simple command is:
help introduction this is the HELP command followed by one argument, 'introduction'. For most commands, each argument's meaning depends on its position in the command line. HELP is the command used to find out about the meaning of each command and its arguments. (See HELP[2] for more on how to use the HELP command). Commands can be entered any time you see a prompt message such as:
CIGAL> (The prompt message may change depending on where you are in the program. Note: the first command word must always be used to find the data one is looking for)

Menus For new users, the easiest way to learn how to use CIGAL is through its menu feature. A CIGAL menu is simply a list of entries, each of which has a command or group of commands associated with it; when you select a menu entry, CIGAL executes the list of associated commands. Most menus are displayed on the screen with a short description for each entry. One chooses an entry simply by moving the cursor to the appropriate line, using the arrow keys on the keyboard, or by moving the 'mouse' or 'tablet' pointer if one is available. You execute the selected command by pressing the key (or by pressing the left button on the mouse or one of the tablet buttons). While using menus you are not limited to the commands that listed on that menu; the prompt message is almost always displayed at the bottom of the screen so you can also execute any other CIGAL command just by typing it in.

For a list of general help topics, see TOPICS[1] For more help on using CIGAL commands, see SYNTAX[1] For more help on using menus, see MENUS[1]