Convert following code for 3d plot in MATLAB into code for Gnuplot?

Question

I have the following 3d plot in MATLAB that I'm trying to plot in Gnuplot but don't know how to. In MATLAB, the x,y,z are matrices that are calculated inside a nested for loop, then plotted:

w = 50 ;
ww = 0:1:w  ;             
d = 100 ;
dd = 0:1:d  ;            

for i=1:1:length(ww)           
    for j=1:1:length(dd)       
        x(i,j) = dd(i) ;   % need to refer to array dd
        y(i,j) = dd(j) ;   
        z(i,j) = <A complicated function ommitted for simplicity>
    end                
end

plot3(x,y,z)

How would I plot the above in Gnuplot? I need to do it for arbitrary values of w and d. I understand that I need the splot function but I am at a loss as to how to implement the calculation of the x,y,z matrices. Help will be appreciated!

Edit: It seems like the above can be done using the array and word keywords/function but I haven't been able to implement it yet

Christoph · Accepted Answer · 2016-06-02 06:32:52Z

1

In gnuplot, simply set your ranges and plot the function:

set xrange [0:50]
set yrange [0:100]
z(x,y) = exp(-(x**2 + y**2)/100.0)
splot z(x, y)

If you want to change the grid, use set isosamples to do that, like

set isosamples 51,101

answered Jun 2, 2016 at 6:32

Christoph

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1 Comment

user1420 Over a year ago

Holy Moly, That's so simple ;D Thanks! I got what I wanted

lostbard · Accepted Answer · 2016-06-02 01:46:44Z

0

You could somewhat cheat, and create the gnuplot plot file from GNU Octave https://www.gnu.org/software/octave/

Assuking you have Octave installed:

Set the graphics toolkit in octave to gnuplot:

graphics_toolkit gnuplot

Then run your p[lot script.

Then dump it to a gnuplot file (assuming running in linux - in windows the x11 and /dev/null would need to change):

drawnow ("x11", "/dev/null", false, "gnuplot.gpt")

There should now be a file gnuplot.gpt that can be loaded by gnuplot - console command:

gnuplot -p gnuplot.gpt

answered Jun 2, 2016 at 1:46

lostbard

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2 Comments

user1420 Over a year ago

I didn't know Octave could generate gnuplot scripts. Will try this out and get back

user1420 Over a year ago

While I was able to generate the plot and the gnuplot script, I need the proper gnuplot code in order to integrate it with an existing script. The code generated this way isn't proper code so I can't accept this answer.

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