Re: Minuit2

Hello Lorenzo,

I your example that I already saw, the function is a Gaussian,, ie is ready to go, how do I instanciate 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
==========================================================================