Re: How to change the TF2 fitter?

From: Vassili Maroussov <Vassili.Maroussov_at_cern.ch>
Date: Fri, 9 Jul 2010 13:19:03 +0200

Dear Rene,

I tried to switch the fitter with the script attached. The script is supposed to find the minimum of TF2 at x=1, y=2. Here are 2 ROOT session, first one with the script compiled, second one with the "bare" CINT

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[vmarouss_at_Ezhik-HDX18 NeuLPulse]$ root

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• *
• W E L C O M E to R O O T *
• *
• Version 5.27/05 30 June 2010 *
• *
• You are welcome to visit our Web site *
• http://root.cern.ch *
• *

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ROOT 5.27/05 (trunk_at_34360, Jul 09 2010, 13:00:25 on linuxx8664gcc)

CINT/ROOT C/C++ Interpreter version 5.18.00, July 2, 2010 Type ? for help. Commands must be C++ statements. Enclose multiple statements between { }. root [0] .x CheckFitter.C+

Minuit: Minimum found at x = 1 y = 2

Fumili: Minimum found at x = 1.16667 y = 2.16667

Minuit2: TFitterMinuit::fit method F2Minimizer is not supported ! root.exe: math/minuit2/src/TFitterMinuit.cxx:716: virtual void TFitterMinuit::SetFitMethod(const char*): Assertion `fMinuitFCN != 0' failed.
[vmarouss_at_Ezhik-HDX18 NeuLPulse]$
[vmarouss_at_Ezhik-HDX18 NeuLPulse]$ root

---

• *
• W E L C O M E to R O O T *
• *
• Version 5.27/05 30 June 2010 *
• *
• You are welcome to visit our Web site *
• http://root.cern.ch *
• *

  ---

ROOT 5.27/05 (trunk_at_34360, Jul 09 2010, 13:00:25 on linuxx8664gcc)

CINT/ROOT C/C++ Interpreter version 5.18.00, July 2, 2010 Type ? for help. Commands must be C++ statements. Enclose multiple statements between { }. root [0] .x CheckFitter.C

Minuit: MINUIT WARNING IN HESSE

• Second derivative zero for parameter1 MINUIT WARNING IN HESSE
• Second derivative zero for parameter1 Minimum found at x = 1.16667 y = 2.16667

Fumili: Minimum found at x = 1.16667 y = 2.16667

Minuit2: TFitterMinuit::fit method F2Minimizer is not supported ! root.exe: math/minuit2/src/TFitterMinuit.cxx:716: virtual void TFitterMinuit::SetFitMethod(const char*): Assertion `fMinuitFCN != 0' failed.
[vmarouss_at_Ezhik-HDX18 NeuLPulse]$

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As it can be seen, only the compiled script with Minuit worked properly. In both cases ROOT crashed at the attempt to use Minuit2 as the fitter for TF2... Something is wrong.

Best regards,

Vassili

On 07/09/2010 08:34 AM, Rene Brun wrote:

> Yes, the default fitter is Minuit. You can select Minuit2, Fumili
>
> Rene brun
>
>
> Vassili Maroussov wrote:
>> Dear ROOTers,
>>
>> How can I change the fitter type which TF2 uses to find the minimum? 
>> Does the TVirtualFitter::SetDefaultFitter() do that?
>>
>> Regards,
>>
>> Vassili
>>
>







text/x-c++src attachment: CheckFitter.C

Received on Fri Jul 09 2010 - 13:19:14 CEST