RE: TH2D in polar coords

Hi,

As documented here the option POL should be used with LEGO and SURF options: http://root.cern.ch/root/html/THistPainter.html#HP19

Cheers, Olivier

From: owner-roottalk_at_root.cern.ch [mailto:owner-roottalk_at_root.cern.ch] On Behalf Of Jakub Cermák Sent: Monday, July 13, 2009 4:26 PM
To: roottalk (Mailing list discussing all aspects of the ROOT system.) Subject: [ROOT] TH2D in polar coords

Hello rooters,
I'm trying to make an 2D histogram in polar coordinates (I wanna visualize the sky - the azimuth and elevation angles). According to manual x should be angle and y radius (length?). But I can't just get it to work. Is there any HOW-TO?

My code:

        TH2D *hist=new TH2D("hist","hist", 90, -90, 90, 90, -90, 90);
        for(int i=0; i<10000;++i)
        {
                double y=gRandom->Uniform(90);
                double x=gRandom->Uniform(M_PI*2);
                hist->Fill(x,y);
        }
        hist->Draw("COLZ POL");

And it makes histogram like http://dl.jcermak.cz/rootpolar.png although I think it should make a circle 180 in diameter and in center in (0,0). Can you please tell me what I'm doing wrong?

Best regards,
Jakub Cermak

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