Adds the graph of
x to the previous
plot created using
goplot, through the external
"gnuplot" program, if that program is available.
If only one of
y are specified, then
it is interpreted as
y and provides the y coordinates of
the data points to plot, with default x coordinates. If both are
specified, then they must have the same dimensional structure. Then
the x coordinates are taken from
x and the y coordinates
are taken from
ltype is a positive integer that selects the line type.
ptype is a positive integer that selects the point type.
dtype is a positive integer that selects the dash type.
Depending on which of these are specified, you get a graph showing
lines, symbols, or both.
color is text specifying which color to use.
legend specifies the text with which to identify the
graph in the legend in the plot.