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Groups > comp.graphics.apps.gnuplot > #4041

Re: Substract value from contour line to surface

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Le mardi 18 septembre 2018 07:47:00 UTC+2, Karl Ratzsch a écrit :
> Am 18.09.2018 um 07:08 schrieb laterite@laposte.net:
> > Le lundi 17 septembre 2018 22:25:51 UTC+2, Hans-Bernhard Bröker a écrit :
> >> Am 17.09.2018 um 17:17 schrieb laterite@laposte.net:
> >>> Hi,
> >>>
> >>> I have an analytical 2D function G(x,y) and a .dat file giving me the x0,y0 points solution of the equation G(x0,y0)=0 in a .dat file.
> >>
> >> There is not really such a thing as "the" points that fulfill that 
> >> criterion --- at least none where that whole set fits into a finite-size 
> >> data file.  So let's say you have some subset of that in a file.
> >>
> >>> Now, I would like to plot the surface of the function G(x,y0)-G(x0,y0).
> >>
> >> How isn't that the exact same surface as G(x,y) itself?  You've just 
> >> renamed the second independent variable and subtracted a constant zero!
> > 
> > 
> > Sorry, my bad, I made a mistake in my explanation :
> > 
> > I have an analytical 2D function G(x,y) and a .dat file giving me a subset of x0,y0 points solution of the equation dG/dx|_y=0 in a .dat file.
> > 
> > And no I want to plot G(x,y0)-G(x0,y0)
> > 
> 
> What are x0 and y0, i.e. which pair from your solution data file do you
> want to use for this plot?
> 
> Or do you want the set of all those curves?

I want to plot the surface of those.

My set of x0,y0 looks like :
# x0, y0, 0
 0.73584  9.4  0 
 0.737374  9.48847  0 
 0.739276  9.6  0 
 0.742614  9.8  0 
 0.745882  10  0 
 0.747475  10.0996  0 
 0.749052  10.2  0 
 0.752131  10.4  0 

And in my plot, I would like to have something like :
splot   (G(x,1,y,0,0)-G(x0,1,$2,0,0)) 
------------------------------
I tried to add the x0 values at the end of a data grid in a dat file like :
#x,y,G(x,1,y,0,0), u or i, x0
0	0.2	0	u	0.124771
0.010101	0.2	-15064.8	i	0.124771
0.020202	0.2	-11467.5	i	0.124771
0.030303	0.2	-9288.36	i	0.124771
0.040404	0.2	-7684.06	i	0.124771
0.0505051	0.2	-6389.49	i	0.124771
0.0606061	0.2	-5285.68	i	0.124771


and tried the command : 
splot   'data.dat' u 1:2:(G($1,1,$2,0,0)-G($5,1,$2,0,0))

but it is not working as G(x,y)-G(x0,y0) is not equal to 0 at x0,y0 while it should by definition.

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Thread

Substract value from contour line to surface "laterite@laposte.net" <hematitefr@gmail.com> - 2018-09-17 08:17 -0700
  Re: Substract value from contour line to surface Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2018-09-17 22:25 +0200
    Re: Substract value from contour line to surface "laterite@laposte.net" <hematitefr@gmail.com> - 2018-09-17 22:08 -0700
      Re: Substract value from contour line to surface Karl Ratzsch <mail.kfr@gmx.net> - 2018-09-18 07:46 +0200
        Re: Substract value from contour line to surface "laterite@laposte.net" <hematitefr@gmail.com> - 2018-09-18 00:36 -0700
          Re: Substract value from contour line to surface Gavin Buxton <gavinbuxton@gmail.com> - 2018-09-18 07:34 -0700
          Re: Substract value from contour line to surface Karl Ratzsch <mail.kfr@gmx.net> - 2018-09-18 17:43 +0200
      Re: Substract value from contour line to surface Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2018-09-18 20:11 +0200

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