Re: [ROOT] Small values can not be displayed ?

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Dec 18 2001 - 21:55:33 MET


Ho Harufumi, Otto,
I have added a fix for this problem in the CVS source.

Rene Brun

On Tue, 18 Dec 2001, Otto Schaile wrote:

> Hi Harufumi,
> the following macro should work:
> 
> {
> Double_t x[7] = {1.0,     2.5,     4.0,     7.0,     
>                  10.0,    30.0,    60.0}; 
> Double_t y[7] = {1.5e-11, 3.0e-12, 1.7e-12, 4.0e-13, 
>                  4.0e-15, 4.0e-14, 2.0e-16}; 
> Double_t ye[7]= {4.0e-12, 1.0e-12, 8.0e-13, 1.0e-13, 
>                  7.0e-15, 3.0e-14, 4.0e-16}; 
> 
> TCanvas * c1 = new TCanvas("c1","c1");
> c1->SetLogx(); c1->SetLogy();
> TGraphErrors *gr = new TGraphErrors(7, x, y, 0, ye);
> gr->Draw("AP");
> 
> // force new min/max
> // Note: only after gr->Draw Histogram exists
> 
> gr->GetHistogram()->SetMaximum(1e-10);
> gr->GetHistogram()->SetMinimum(1e-18);
> c1->Modified(kTRUE);
> }
> --------------------------------------------------------------
> 
> I guess root cannot / does not draw points with negative
> values or errors in log scale.
> Note point 7: 2.0e-16, with errors: minus 2.0e-16 to plus 6.0e-16
> 
> Cheers
> Otto
> 
> On Tue, 18 Dec 2001, Harufumi Tsuchiya wrote:
> 
> > 
> > Hi ROOTers.
> > 
> > I have the data which must be displayed in log scale.
> > The data is like below.
> > 
> > x      y        yerror
> > 1.0   1.5e-11 4.0e-12
> > 2.5   3.0e-12 1.0e-12
> > 4.0   1.7e-12 8.0e-13
> > 7.0   4.0e-13 1.0e-13
> > 10.0  4.0e-15 7.0e-15
> > 30.0  4.0e-14 3.0e-14
> > 60.0  2.0e-16 4.0e-16
> > 
> > As I would like to show data with error bars, I used TGraphErrors.
> > 
> > c1->SetLogx(); c1->SetLogy();
> > TGraphErrors *gr = new TGraphErrors(ndata, x, y, 0, yerror)
> > gr->Draw("AP")
> > 
> > But I could not get all data points with errors.
> > As I attached this e-mail, the data point with x = 10.0 and 60.0 were not
> > appeared on graph. Other data points appeared together with errorbars.
> > 
> > I thought that if the values of the data points were smaller than errors,
> > the data point and the accompanied errors were not drawn.
> > Is is correct ?
> > 
> > If someone know the method to avoid the my uncomplete result, 
> > Please tell me.
> > I would like to show all data points with error bars.
> > 
> > I use ROOT v 3.02.06 on IRIX64 and g++ 2.95.2.
> > 
> > Thanks
> > 
> > Harufumi Tsuchiya
> > 
> > 
> > 
> 
> -- 
> Otto Schaile            Sektion Physik, LMU Muenchen
> Phone: +49 89 289 14070     Am Coulombwall 1, D-85748 Garching, Germany
> GSM:   +49 160 1553598
> FAX:   +49 89 289 14072     EMail: Otto.Schaile@Physik.Uni-Muenchen.DE
> 



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