Re: [ROOT] TGaxis with function

From: Tommaso Chiarusi (Tommaso.Chiarusi@bo.infn.it)
Date: Wed Mar 10 2004 - 18:05:10 MET


Hi Olivier,
you were right, I made a mistake, in fact the real algorithm is

    if(x[0]<=90) fu = 90 - x[0];
    else fu = 90-x[0]; 

and not 
    else fu = x[0]-270; 

Well yesterday I fused...:) 


buy the way the devicing fact is that, neither with the 
correct algorithm, the labels on to  the plot are not modified 
accordingly!!!
In fact I get simply 
180 160 140 120 100 80 60 40 20 0

Moreover, if in the function you set:
      fu = x[0]*2;

just for trying, you get no effect on the range.

may be I didn't well understand how TGaxis works with a function.

any suggestion?
Thank you.
Tommaso

On Wed, 10 Mar 2004, Olivier Couet wrote:

> 
> Hi Tommaso,
> 
>  I looked closer at your examples. I agree with you that the first one 
> transform the following labels:
> 
> -80 -60 -40 -20  0  20  40  60  80
> 
> into:
> 
>  80  60  40  20  0 -20 -40 -60 -80
> 
> But, seems to me the 2nd example transform:
>  
>   0  20  40  60  80  100  120  140  160 180
> 
> into:
> 
>  90  70  50  30  10 -170 -150 -130 -110 -90
> 
>  Which, I guess, is not what you want. I think you did a mistake in your 
> 2nd example.
> 
>  Cheers,      Olivier
> 
> 
> On Tue, 9 Mar 2004, Tommaso Chiarusi wrote:
> 
> > 
> > Hello everybody:
> > 
> > OS Linux RH 9
> > ROOT 3.10/02  16 December 2003
> > 
> > well, I need to reset the labels onto an histogram.
> > It has the x axis which ranges from 0 to +180
> > I like it to span from +90 to -90 (yes from positive to negative
> > like 90 80 70..10 0 -10 ... -80 -90).
> > 
> > So decided to  
> > TGaxis method together with a function
> > 
> > 
> > So I've written the function:
> > 
> > double funz(double *x,double *par)
> > {
> >   double fu=0;
> >   fu = -x[0];
> >   return fu;
> > }
> > 
> > and in the body of the macro, 
> > 
> >  TF1 *f = new TF1("f",funz,-90,90,0);
> >  TGaxis *tga = new TGaxis(0,0,180,0,"f",510);
> >  tga->Draw();
> > 
> > and it works!
> > 
> > note that the spanning of the new scale is independent from the original
> > range.
> > -----
> > THE QUESTION:
> > 
> > Why the following doesn't give the same result?
> > 
> > I redefine the function,
> > 
> > double funz(double *x,double *par)
> > {
> >   double fu=0;
> >   if(x[0]<=90) fu = 90 -x[0];
> >   if(x[0]>90) fu = x[0]-270;
> > 
> >   return fu;
> > }
> >                                                                                                  
> > and in the body of the macro,
> >                                                                                                  
> >  TF1 *f = new TF1("f",funz,0,180,0);
> >  TGaxis *tga = new TGaxis(0,0,180,0,"f",510);
> >  tga->Draw();
> > 
> > note the different range for f
> > 
> > Best regards, Tommaso
> > 
> > P.S.
> > is this mailing list hard-contamined by spam?
> > is it true that it will be removed by the CERN mailing list?
> > 
> > 
> > 
> > 
> 
> 

-- 
-----------------------

Dr. Tommaso Chiarusi 

Dipartimento di Fisica 
Universita' di Bologna
INFN. Sez. Bologna

Tel +39.051.209.5234 
Fax +39.051.209.5269

-----------------------



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