Scilab is available for free via the Internet. The primary site is ftp.inria.fr under INRIA/Projects/Meta2/Scilab. However, it also appears on sunsite.unc.edu, under pub/Linux/apps/math/matrix, and the other mirror sites, such as tsx-11.mit.edu or smug.student.adelaide.edu.au. It's a bit voluminous, just over 5 megabytes for the compiled Linux version (in tarred gzipped form). You need to unpack it and follow the two simple directions in the README file, section I.A. You might also add scilab's bin directory to your PATH.
If scilab doesn't come up in color, then you will need to modify your .Xdefaults file by adding “*customization: -color ” to the end of the file. Then use xrdb .Xdefaults to force the change.
The copyright agreement is that “INRIA freely grants you the right to use, modify and integrate SCILAB in another program provided” that their copyright notice appears in all copies and you acknowledge receiving SCILAB by returning an agreement, provided in the main directory, to this effect,
For those of you who want to install scilab on your home machine from your work machine, and are wondering how to get a 5 MB file on floppy disks: try using the GNU tar multi-volume command: tar -cMf /dev/fd1 scilab-2.0-Linux.tar.gz, where /dev/fd1 is to be replaced by the device name for your work computer's floppy drive. Just change files when prompted. This works the same at the other end, except that you use tar -xMf /dev/fd1.