gnuplot-info

[Gnuplot-info] putting a dot on a graph or surface to mark a spot - how?

[Esmail <eb...@ho...>]

Hello all,

(just discovered this group)

I am plotting some graphs and surfaces using gnuplot using plot and
spot. These are functions that I am optimizing. So far so good.

What I would like to do, but don't know how, is to place some sort of
a marker or circle on the graph or the surface to indicate the maximum
location found. Ie I would draw the graph or surface first, and then
mark/superimpose a marker to show the maximum spot.

Is there a way to do this? I've been using gnuplot itself for
a while, but I have no idea how to do this.

Thanks,
Esmail

ps: I am mainly using gnuplot version 4.2 patchlevel 4 under Linux.

Re: [Gnuplot-info] putting a dot on a graph or surface to mark a spot - how?

[Dr. I. D. J. <die...@t-...>]

Dear Esmail,
maybe "set label" can be your friend? See help set label how it works, in my 
opinion it would be best to place a point with an empty text at "position" and 
manually put a texlabel (if you want) in the vicinity of the point.
Hope this helps,
take care



Dieter

Example:

f(x)=x*x+0.5
set samples 1000
set grid
set xrange[-1:1]
set yrange[0:1]
set label 1 " " center front at graph 0.5,0.5 point pt 7 ps 1
set label 2 "Point" at graph 0.52,0.45
plot f(x) w l lw 2


Am Sonntag 02 August 2009 02:08:59 schrieb Esmail:
> Hello all,
>
> (just discovered this group)
>
> I am plotting some graphs and surfaces using gnuplot using plot and
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if you really want to see the pictures above - use some font
with constant spacing like courier! :-)
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Re: [Gnuplot-info] putting a dot on a graph or surface to mark a spot - how?

[Esmail <eb...@ho...>]

Dr. Ing. Dieter Jurzitza wrote:
> Dear Esmail,
> maybe "set label" can be your friend? See help set label how it works, in my 
> opinion it would be best to place a point with an empty text at "position" and 
> manually put a texlabel (if you want) in the vicinity of the point.
> Hope this helps,
> take care

Hallo Dieter,

Many thanks, your suggestion helped a great deal and got me to
dig more into gnuplot (I hadn't used much of the label command before).

When I leave out 'graph' in the 'at graph' part of the command I can
position the point better using the coordinates in the plot itself
(rather than window based coordinates?).

This also seems to be working just fine for 3D plots via splot as
all I seem to do is add a 3rd coordinate to the position.

thank again for the great help,

Esmail