Re: [ROOT] Interactive minuit access from ROOT?

From: Arthur E. Snyder (snyder@SLAC.stanford.edu)
Date: Mon Dec 03 2001 - 08:05:55 MET


The SetParLimits function really seems to be totally ineffective:

root [180] efit->GetParameter(0)
(Double_t)5.89071269118343935e+02
root [181] efit->SetParameter(0,2.0)
root [182] efit->GetParameter(0)
(Double_t)2.00000000000000000e+00
root [183] efit->SetParLimits(0,1.0,1.0)

-so parmeter 0 of this function (a "pol4") should be fixed to 2.0

root [184] bhist->Fit("e")  [note a]
 FCN=66.7558 FROM MIGRAD    STATUS=CONVERGED     134 CALLS         135
TOTAL
                     EDM=5.71703e-14    STRATEGY= 1      ERR MATRIX NOT
POS-DEF
  EXT PARAMETER                APPROXIMATE        STEP         FIRST
  NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE
   1  p0           5.89071e+02     fixed
   2  p1          -3.16776e+03   2.00304e+00   1.51050e-03   8.00435e-08
   3  p2           6.43575e+03   3.89200e+00   3.06881e-03  -8.40017e-09
   4  p3          -5.79772e+03   4.44730e+00   2.76457e-03   9.71526e-09
   5  p4           1.94450e+03   3.58314e+00   1.54134e-03   6.48922e-08

-it fits parameter 0 though claiming it is fixed!?

-am I doing somthing real stupid or is this a bug?

Art S.

note a: "e" is the name I gave the TF1 function *efit. BTW, the function
TH1::Fit(TF1*) also seems to be missing in action, so I have to use the
one that finds the function by name rather than pointer.

A.E. Snyder, Group EC                        \!c*p?/
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Box 4349                                        |
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On Sun, 2 Dec 2001, Rene Brun wrote:

> Art,
>
> Even in PAW, people included the Minuit commands in a KUIP macro.
> You should do the same. However, currently, it is not easy to get
> the control after each iteration. You get the control only at the end
> of the fit, unless you implement your own fitting model (like
> H1FitChisquare or likelihood). One could imagine a new option
> to force a call to a function or macro after each iteration.
> If there are more suggestions, they are welcome.
>
> Rene Brun
>
> On Sun, 2 Dec 2001, Arthur E. Snyder wrote:
>
> > Hi Rene,
> >
> > I was able to grab gMinuit and use mnexcm to execute minuit commands, refit,
> > etc. It is pretty awkward interactively, but works. However, the results do
> > not propagate back to the function attached to my histogram, so when I
> > redraw it I see the result of the original default fit. Also, if I refit it
> > seems to start again from scratch and forget any 'fix' or 'set par' I've
> > done to gMinuit object.
> >
> > Perhaps, I would be better off using the get/set functions provided in TF1?
> > It looks pretty easy to write my own little macro to manipulate these
> > functions with minimal typing ...
> >
> > Art
> >
> >
> > ----- Original Message -----
> > From: "Rene Brun" <brun@pcbrun.cern.ch>
> > To: "Arthur E. Snyder" <snyder@SLAC.Stanford.EDU>
> > Cc: <roottalk@pcroot.cern.ch>
> > Sent: Sunday, December 02, 2001 1:39 PM
> > Subject: Re: [ROOT] Interactive minuit access from ROOT?
> >
> >
> > > Use the global gMinuit
> > >
> > > Rene Brun
> > >
> > > On Sun, 2 Dec 2001, Arthur E. Snyder wrote:
> > >
> > > > Thanks, Rene. Can you tell me how I access TMinuit object when I'm
> > fitting a
> > > > histogram? I don't find an assessor either in TF1 or TH1. I've also
> > looked
> > > > up the inheritance tree but don't find anything that looks like the
> > right
> > > > thing.
> > > >
> > > > Art
> > > >
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: "Rene Brun" <brun@pcbrun.cern.ch>
> > > > To: "Arthur E. Snyder" <snyder@SLAC.Stanford.EDU>
> > > > Cc: <roottalk@pcroot.cern.ch>
> > > > Sent: Sunday, December 02, 2001 9:49 AM
> > > > Subject: Re: [ROOT] Interactive minuit access from ROOT?
> > > >
> > > >
> > > > > Hi Art,
> > > > >
> > > > > The direct equivalent of PAW option "M" does not exist.
> > > > > However, you can invoke any function from TMinuit directly.
> > > > > This should provide even more flexibility at the expense
> > > > > of slightly more typing.
> > > > >
> > > > > Rene Brun
> > > > >
> > > > > On Sat, 1 Dec 2001, Arthur E. Snyder wrote:
> > > > >
> > > > > > Try again to post this with more sensible subject line!
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > From: "Arthur E. Snyder" <snyder@SLAC.Stanford.EDU>
> > > > > > To: <roottalk@pcroot.cern.ch>
> > > > > > Sent: Saturday, December 01, 2001 12:29 AM
> > > > > > Subject: Re: [ROOT] tiny Bug in root
> > > > > >
> > > > > >
> > > > > > > Is it possible to invoke interactive minuit from within ROOT?
> > I.e.,
> > > > the
> > > > > > > equivalent of 'h/fit 100 myfunc.f m' in paw? The ROOT fit provides
> > > > most of
> > > > > > > the options of paw, but not this one. The 'm' option in ROOT seems
> > to
> > > > be
> > > > > > > something different.
> > > > > > >
> > > > > > > I've looked in TMinuit, TF, and TH1 classes, but have not been
> > able to
> > > > > > find
> > > > > > > anyway to get to the interactive interface of minuit or some
> > > > alternative.
> > > > > > >
> > > > > > > Art Snyder at SLAC
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > >
> >
>



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