Re: Minuit2

Hello,

Could somebody reply to my emaik ?
Thank.
>
> I know the example and my comment is, the function is a
Gaussian,, ie is ready
> to go, how do I build my own function ? Previously, I
> overload the () operator.
>
> Thank.
>
> Regards.
>
>> Hello Patrick,
>>
>> the ModularFunctionMinimizer is an abstract class, you need to instantiate
>> a derived class, depending on the algorithm you want to use.
>> FOr example for Migrad (a variable metric minimizer) you need to
>> instantiate the VarableMetricMinimizer class.
>> You can do as following:
>>
>> VaraibleMetricMinimizer minimizer;
>> FunctionMinimum min = minimizer.Minimize(*fFCN, par, stra, 0, 0.1);
>>
>> One examples is in SVN in
>> $ROOTSYS/math/minuit2/test/MnSim/DemoGaussSim.cxx
>> available also online at
>>
>> http://root.cern.ch/viewvc/trunk/math/minuit2/test/MnSim/DemoGaussSim.cxx?view=markup
>>
>> Best Regards
>> Lorenzo
>>
>> On Sep 14, 2008, at 8:16 PM, Patrick Dupre wrote:
>>
>>> Hello,
>>>
>>> I used the Minuit2 package by derivating a class from FCNBase and by
>>> overloading the operator () as it is suggested in the manual:
>>> mnusersguide.pdf
>>> I works, but to improve the control on the fit I wanted to use:
>>> ModularFunctionMinimizer
>>> So I tried to instantiate the class by:
>>> ModularFunctionMinimizer minimizer (*fFCN, par, stra, 0, 0.1) ;
>>> where:
>>> RR_Chi2 *fFCN ;
>>> and where RR_Chi2 is a class derivated from FCNBase (the one that I used
>>> before) previously instanciated (fFCN = new RR_Chi2 (x, y))
>>>
>>>
>>> I get the following compilation error:
>>>
>>> Fitter.cpp: In member function 'std::vector<std::vector<double,
>>> std::allocator<double> >, std::allocator<std::vector<double,
>>> std::allocator<double> > > > ROOT::Minuit2::Fit_RR::Fit()':
>>> Fitter.cpp:418: error: no matching function for call to
>>> 'ROOT::Minuit2::ModularFunctionMinimizer::ModularFunctionMinimizer(ROOT::Minuit2::RR_Chi2&,
>>> ROOT::Minuit2::MnUserParameters&, ROOT::Minuit2::MnStrategy&, int,
>>> double)'
>>> /usr/local/include/Minuit2/ModularFunctionMinimizer.h:47: note: candidates
>>> are: ROOT::Minuit2::ModularFunctionMinimizer::ModularFunctionMinimizer()
>>> /usr/local/include/Minuit2/ModularFunctionMinimizer.h:47: note:
>>> ROOT::Minuit2::ModularFunctionMinimizer::ModularFunctionMinimizer(const
>>> ROOT::Minuit2::ModularFunctionMinimizer&)
>>> Fitter.cpp:418: error: cannot declare variable 'minimizer' to be of
>>> abstract type 'ROOT::Minuit2::ModularFunctionMinimizer'
>>> /usr/local/include/Minuit2/ModularFunctionMinimizer.h:47: note: because
>>> the following virtual functions are pure within
>>> 'ROOT::Minuit2::ModularFunctionMinimizer':
>>> /usr/local/include/Minuit2/ModularFunctionMinimizer.h:86: note: virtual
>>> const ROOT::Minuit2::MinimumSeedGenerator&
>>> ROOT::Minuit2::ModularFunctionMinimizer::SeedGenerator() const
>>> /usr/local/include/Minuit2/ModularFunctionMinimizer.h:87: note: virtual
>>> const ROOT::Minuit2::MinimumBuilder&
>>> ROOT::Minuit2::ModularFunctionMinimizer::Builder() const
>>>
>>> So, it looks like that I cannot instanciate a class
>>> ModularFunctionMinimizer that way.
>>> Question 1) how can I do it by keeping my previous code
>>> 2) If I have to rewrite my previous code, can I get an example ?
>>>
>>> Thank.
>>>
>>>
>>> --
>>> ---
>>> ==========================================================================
>>> Patrick DUPRÉ | |
>>> Department of Chemistry | | Phone: (44)-(0)-1904-434384
>>> The University of York | | Fax: (44)-(0)-1904-432516
>>> Heslington | |
>>> York YO10 5DD United Kingdom | | email: pd520_at_york.ac.uk
>>> ==========================================================================
>>
>>
>
>

-- 
---
==========================================================================
  Patrick DUPRÉ                      |   |
  Department of Chemistry            |   |    Phone: (44)-(0)-1904-434384
  The University of York             |   |    Fax:   (44)-(0)-1904-432516
  Heslington                         |   |
  York YO10 5DD  United Kingdom      |   |    email: pd520_at_york.ac.uk
==========================================================================