Re: [ROOT] TGaxis

From: Valeri Fine (fine@bnl.gov)
Date: Tue Jun 05 2001 - 02:10:56 MEST


Hello Mike
I assume you have some access to STAR framework and can use the 
class TColoredAxis from $STAR/StRoot/STEventDispolayMaker packages
If it doesn't match your needs it can be enhanced as well.

 Hope this helps
               With my regards,  Valeri
 
----- Original Message ----- 
From: "Mike Miller" <miller@star.physics.yale.edu>
To: <roottalk@pcroot.cern.ch>
Sent: Monday, June 04, 2001 6:47 PM
Subject: [ROOT] TGaxis


> Hello all, I'm trying do the following:
> 
> I have a 1-d histogram that I draw.  I then want to add some additional
> x-axes that are non-linear.  So, I thought that I could use TGaxis and
> specify a mapping function (TF1) to do so.  However, the result I get is
> crazy, so I must not understand the meanings of the parameters passed to
> the constructor, but the documentation points to TGaxis::PaintAxis and
> that doesn't help very much.
> 
> Can you tell me:
> 
> 1) If xmin, xmax, ymin, ymax specify the endopoints in global coordinates,
> what does that really mean?  If I draw a canvas and then draw a histogram
> on top of it, is the global x,y defined by the axes of the histogram?
> 
> 2) What is ndiv really?  I thought that if it is really the number of
> divisions, then ndiv=300 should give 300 divisions, but this doesn't seem
> to be the case.
> 
> 3) What is the relationship of the mapping that the TF1 should
> establish.  If I have a function F(x) where x is the independent variable
> of my original Histogram, and F(x) has a given range Fmin and Fmax, how do
> I translate this into what TGaxis expects?
> 
> 4) Why does TGaxis have a constructor that takes the char* name of a
> function instead of a pointer to a TF1?  Seems like this is dangerous and
> easy to change...
> 
> 5) I've studied the example macros from TGaxis .html page, and they
> haven't really helped, so can someone please answer my questions without
> pointing to the example?  
> 
> Thanks, Mike
> 
>  Michael L. Miller
> Yale Physics
> michael.miller@yale.edu
> 
> BNL: (631) 344-8342
> Building 118
> Yale Software
> 
> Yale:   (203) 432-5637
> Room 305 WNSL
> 
> 



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