Re: [ROOT] exponents in scaling

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri Nov 22 2002 - 12:35:53 MET


Hi Nick,

 1- You are using the old Windows interface that prompts for a number
    in the SetLogy function. On all other interfaces, this is just a
    toggle. We hope to replace this old interface in the near future
    by the Root standard GUI.

 2- You misunderstood Florian's request. This was for linear axis.
    I gave him a recipee to control somehow the exponent value.
    A better interface could be proposed, but certainly not
    the one with TPad::SetLogy.

 3- When drawing in log scale, the min/max is computed automatically
    from the histogram contents and bins or the max/min.
    Could you send me an example of plot that does not give a correct
    log scale exponent?

Rene Brun

On Fri, 22 Nov 2002, Nick van Eijndhoven wrote:

> Hi Rene,
> Maybe I misunderstand something, but if I have a plot of
> a histo on my canvas and via 'right-clicking' switch to a log
> scale on e.g. the y-axis the popup box prompts me for a number.
> If I enter 0, the y-axis will stay in linear scale.
> If I enter 1, I get a standard log-scale in steps of 10.
> I would expect that if I enter e.g. 3 I would get a log scale
> in steps of 10**3 etc...
> However, I don't think currently it works this way.
> In case I am correct, it seems that this procedure is currently not
> correctly working.
> If I am not correct, could you then please tell me what the number
> means which I have to enter. And furthermore, could a functionality
> like the above be implemented ? This would solve Florian's problems
> and also provide a nice facility to make appropriate plots.
> 
>                                                 Cheers,
>                                                  Nick. 
> 
> Rene Brun wrote:
> > 
> > Hi Florian,
> > 
> > You have some control on the axis exponent with TGaxis::SetMaxDigits
> > Example
> > TH1F h("h","h",100,-2,2);
> > h.SetMaximum(1e5);
> > TGaxis::SetMaxDigits(3);
> > h.Draw();
> > 
> > Rene brun
> > 
> > On Thu, 21 Nov 2002, Florian Schopper wrote:
> > 
> > >
> > > dear rooters,
> > >
> > > is there a way to set the exponents in which the scale of y-axis is given?
> > > We would like to have always multiples of -3 (milli,mikro,nano,pico...).
> > >
> > > cheers
> > >        Florian Schopper
> > >
> > >
> > >
> > > ----------------------------------------------------------------------
> > > Dr. Florian Schopper                  office: MPI Halbleiterlabor
> > >
> > > Ludwig-Merk str. 3                           Otto-Hahn-Ring 6 , Gebäude 72
> > > D-80805 München                              D-81739 München
> > > Germany                                      Germany
> > >
> > >
> > > fax home:   49/89/3226157                  fax HLL:   49/89/839400-13
> > > phone home: 49/89/32455680                 phone HLL: 49/89/839400-33
> > >
> > >                      e-mail: fls@hll.mpg.de
> > >        http://www.gamma.mpe-garching.mpg.de/MEGA/mega.html
> > > ----------------------------------------------------------------------
> > >
> 



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