Re: How do you plot dashed lines?

[Jonathan Stickel]

Dmitri A. Sergatskov wrote:
> Vic Norton wrote:
>
> > How do you plot dashed lines in octave? I'm using gnuplot. The MatLab 
> > format
> >    octave> plot(F(1, :), F(2, :), "--")
> > just produces a solid red line.
> >    octave> plot(F(1, :), F(2, :), "b--")
> > changes the line to blue, but it is still solid.
> >
> > So how do you get dashes?
>
>
> The short answer -- you cannot. The long answer is -- it depends on the 
> terminal
> that gnuplot is using. You can issue "test " command to gnuplot to see all
> capabilities of the  terminal you are using. I can tell you that e.g. 
> X11 terminal
> does not have dashed lines and postscript does have. You would have to
> investigate the others. Also if you are to use postscript terminal you
> would have to use low-level plotting using "gset" etc...
>
> One option would be using "fig" terminal and then edit the final picture
> in xfig.

gnuplot can be a very complex but useful program.  If you plot a number 
of lines in octave, by default they will show as different colored solid 
lines in X11.  But if you then "print" the graph to a file like this 
(needs octave-forge and mark_as_command("print")):

octave> print -deps "output.eps"

You will get a black and white eps graphic with the lines differentiated 
by dash patterns.  Although I thought this strange at first, I decided I 
liked this behavior.  X11 is for visualizing the data, and color works 
great for that.  But a print graphic is often best in black and white, 
as long as the dash patterns are appropriate.

To customize color and dash patterns, you will need to use the low-level 
gnuplot commands as described in the gnuplot manual 
(http://www.bmsc.washington.edu/people/merritt/gnuplot/gnuplot.pdf).

Jonathan



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