"Lsys" is a program for manipulating systems of linear equations,
written by Mark Ellingham.

Lsys commands (version 0.14)
============================

    Variable names must begin with a letter and contain only letters,
digits or the underscore character.  System names must begin with
a letter but may then contain any non-whitespace character. 
Equation names are of the form "e1", "e2", and so on.
    Rational numbers may be given following any of the following
patterns, with optional plus or minus sign in front.
	1	31/40	7_1/2 (i.e. seven and a half)
Be careful: 2/3x means (2/3) x, not 2/(3x).
    The program works always on a current system, called
"CURRENT".  This may be saved to systems with other names, or
recalled from those systems.

help		Print help messages.
help on <topic>

quit		Leave the program.

read		Read a system of linear equations: separate equations by
		commas, terminate with a period.
read <s>	Equivalent to "read" followed by "save as <s>".

save		Save a system under the name by which it was last saved or
		selected.
save as <s>	Save a system under the name <s> .

undo		Undo last command that altered a system, to
		whatever extent possible.  This command can only
		undo the changes to ONE matrix, so if both the
		current matrix and a stored matrix are changed by
		a command, this command undoes only the changes
		to the stored matrix.

list		List all available systems (with numbers of
		equations and variables).

delete system <s> ...
delete equation <e> ...
delete variable <v> ...
		Delete the appropriate type of object.  Note that
		the "delete equation" and "delete variable"
		commands affect only the current system.

print <s> ...	Print the listed systems.  If no systems given,
		prints current system.

solve <e> for <v>
		Solves given equation for given variable.

substitute for <v> from <e> in <s> ...
		Substitutes for variable <v> using equation <e>
		into the named systems.  Instead of a list of
		systems, you may just say "the rest" or just
		"rest" to make substitutions everywhere.

extend		Read more equations into current system.
extend <s>	Select <s>, read more equations into it.  Does
		not save new current system to <s>.

select <s>	Copy <s> to current system.

change <e> ... on <side> to <expression> .
		Change the occurrences of the variables in
		<expression> to look like <expression> in the
		named equations on the named <side> (either "left"
		or "right").  The <expression> may continue onto
		successive lines and must end with a period.
		The list <e> ... can be replaced by "all".

autoprint > filename
autoprint >> filename
autoprint off
                Sets autoprint to overwrite (>) or append to (>>)
                a file, or turns it off.  Autoprint will print the
                current matrix to a file as well as to the screen
                after most commands.

Some of the above may be shortened: "del", "sub", "sel", "ext".