Installing scilab on a mac.

First check to see if the optional system software is installed on
your mac. Look in the utilities sub folder of the Applications folder.
The program you are looking for is called X11. You can start X11
by double clicking. (Starting X11 is necessary only on older systems.) 

If you don't see the application X11, you must install it. X11 comes
on the mac system dvd that came with your mac. It is certainly on 10.5
Leopard and 10.4 Tiger the application is on the dvd. For early versions
of mac os X, X11 was a free download. If you can't find the install
dvd; there are ways of downloading X11 for free. For 10.3, Panther,
one had to download X11 from apple
http://www.apple.com/downloads/macosx/apple/macosx_updates/x11formacosx.html

To install X11 from the dvd:
http://8help.osu.edu/3670.html Tiger
http://8help.osu.edu/3688.html Leopard

Download scilab version 4.1.2-10.4-Intel.zip from
http://www.lmac.utc.fr/~mottelet/Darwin/
if your machine uses the intel chip. If you have an older
PowerPC mac, use version 4.1-10.4-PPC.zip

Scilab Version 5.0.x is not recommended, even for windows. 

Using scilab on a mac

Scilab uses the X11 user interface which is not very mac like. In
particular it expects a 3 button mouse and for the mouse to select
focus. This means
1. The mouse must be in the scilex window before input will be accepted
(in addition to scilex being the current window).
2. If you don't have a 3 button mouse (most laptops for example) you
will want to go into menu's X11 => Preferences => Input and check
mark Emulate three button mouse.
3. The scroll bar on the right is controled by the middle mouse button
(or command button in emulation mode)
4. Copy is highlight, Paste is middle mouse button.

Saving graphics

The command xs2eps(0,'foo.eps') with save the Scilab Graphic (0) to the
file foo.eps as postscript. Double clicking on the file on a mac will
convert to pdf. Or you can drag and drop into a word processing program.