fitting range, passing variables and scaling

From: Alan Clayton Coleman (colemana@jlab.org)
Date: Sat Nov 14 1998 - 22:54:58 MET 




Hi ROOTers,

    I am new to both C++ and ROOT. I have what
hopefully are some simple questions and would request any assistance or
direction. (i.e., I can think of some painful ways to do the following)

1) Is there a simple way to find the value of  the max and min
bin with entries (bin # or "x"-value?) in a histogram?

2) It would be desirable to perform fits over the data in an iterative
fashion, i.e., making differient cuts on a couple of the ntuple parameters
and then fitting.  The fitting consists of a peak and background 
function.  For single fits there are no problems as  values required
by the background function can be entered by hand. But, for multiple fits
for different cut values it is not understood how these changing values
can also be passed to the fitting functions. Is there a way to use global
variables? In addition is there a way to define constant global values? 
I.e.,  for  the latter it would be nice not to define the mass
of a proton in every function.

3) Initially the background function used gives only the shape (based
on fitting parameters),  addition of an amplitude fit parameter in
general distorts the meaning of amplitude. Is there an easy way to scale
the background shape to 1 and  then multiply the amplitude fit parameter?

    Apologies for my ignorance and a great deal of thanks
for any assistance.

-- 
Alan Coleman
colemana@cebaf.gov
W&M Small Hall Rm 307
(757) 221-3543
TJNAF
Bldg 16 Rm 14
(757) 269-7541
http://physics.wm.edu/~coleman/home.html
"Lehrer sind Menschen, die uns helfen probleme zu loesen, die wir ohne sie nicht haetten."
"Teachers are people who help us to solve problems that we would not have without them."

 












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