Hi Nick,
When plotting in log scale with a very large range, Root will
automatically compute the best scale corresponding to the
requested number of primary divisions on the axis (default is 10).
You can change this default with eg, h->GetYaxis()->SetNdivisions(5);
You can also do it from the axis pull down menu.
Rene Brun
On Fri, 22 Nov 2002, Nick van Eijndhoven wrote:
> Hi Rene,
> Thanks for the information; seems I indeed misunderstood Florian.
> Indeed I am using the (old) windows interface.
> The log scale exponents I get are not incorrect, but sometimes
> I would like to have the possibility to determine the 'stepsize'
> (i.e. factors of 10, 100, 1000, ....), certainly when I am plotting
> a histo with a very large range (i.e. cosmic ray fluxes).
> Is there a way to change the 'stepsize' for a log scale ?
>
> Cheers,
> Nick.
>
> Rene Brun wrote:
> >
> > 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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