Plotting 3d (TGraph2D) data

From: Alexander Wagner <>
Date: Thu, 17 Aug 2006 17:42:38 +0200


Could it be that if I want to plot 3d data using a TGraph2D, that the grid is to fine? What I do essentially is using a csv input file looking somewhat like

   x-column y-column z-value

fill it into a TGraph2D object by some read in routine. I find that this works fine as long as the "grid" of the data is not "to fine". That is I have a grid -2000..2000 in both dimensions and I get a suitable plot if I grid it at 200, 400 and so on, but I get essentially a single centred spike at 0,0 once I use a finer grid of 50, 100, 150...

Also I find some (looks like random) spikes once I produce the plot with root compared to the same data feeded to gnuplot.

Could this be an artefact from the delauny interpolation? Or should I search for some bug in my macro? The strange thing is that it happens only if I use to fine a grid...

(Unfortunately the macros involved are not that easily cooked down to 5 essential lines...)

Root is at 5.11 on Debian GNU Linux 3.0.


Kind regards,                /                 War is Peace.
                            |            Freedom is Slavery.
Alexander Wagner            |         Ignorance is Strength.
                            | Theory     : G. Orwell, "1984"
                           /  In practice:   USA, since 2001
Received on Thu Aug 17 2006 - 17:42:46 MEST

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