Format of the command is
name=expression
ArtSGraph evaluates expression and assigns result of evaluation
to the variable, specified by name. Variable and its value are displayed
in Variable Zone. Name may contain letters, digits and underscore,
must begin with a letter and should not exceed 7 characters.
Examples:
n=1 ; assigns value 1 to variable n
s=cos(x) ; assigns value cos(x) to variable s
x=0 ; assigns value 0 to variable x
y=s+n ; assigns value 2 to variable y