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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