Re: gMinuit problem ..

From: Arthur E. Snyder <snyder_at_slac.stanford.edu>
Date: Mon, 15 Jun 2009 17:04:51 -0700

Hi Root Folks,

A stupid question I know .. but how to I set max and min Y range when making a simple scatter plot?

I do

tup->Draw(y:x)

and I'd like to set y range such that when I do

tup->Draw(yp:x,"","same")

I can fit yp on the same plot.

I've looked at trying to manuplate Y-axis of htemp, but can't find what I need. It must be easy but I'm just not finding it ...

-Art S.

A.E. Snyder, Group EC                        \!c*p?/
SLAC Mail Stop #95                          ((.   .))
Box 4349                                        |
Stanford, Ca, USA, 94309                      '\|/`
e-mail:snyder_at_slac.stanford.edu                 o
phone:650-926-2701                              _
http://www.slac.stanford.edu/~snyder          BaBar
FAX:650-926-2657                          Collaboration



On Mon, 2 Mar 2009, Rene Brun wrote:

> Art,
>
> Your analysis is right.
>
> Rene Brun
>
> Arthur E. Snyder wrote:
>> Thanks, Rene. Something similar must be happening with our slightly more
>> complex fit where sometimes gMinuit apprears and other times not.
>>
>> I would guess that if we move the fitting function to pre-defined function
>> rather then a string in the TF1 function this would fix the "problem" as
>> root would no longer be able to see if the function was simple or not and
>> would always have to use Minuit.
>>
>> Does that sound right?
>>
>> -Art
>>
>> A.E. Snyder, Group EC \!c*p?/
>> SLAC Mail Stop #95 ((. .))
>> Box 4349 |
>> Stanford, Ca, USA, 94309 '\|/`
>> e-mail:snyder_at_slac.stanford.edu o
>> phone:650-926-2701 _
>> http://www.slac.stanford.edu/~snyder BaBar
>> FAX:650-926-2657 Collaboration
>>
>>
>>
>> On Sat, 28 Feb 2009, Rene Brun wrote:
>>
>>> Art,
>>>
>>> When fitting with simple functions like polynomials, TMinuit is not used,
>>> only the linear fitter (TLinearFitter). The linear fitter is much faster
>>> than Minuit. You can force fitting of a polynomial with Minuit by
>>> specifying the fit option "L", see documentation of TH1::Fit
>>>
>>> Rene Brun
>>>
>>> Arthur E. Snyder wrote:
>>>>
>>>> Rene et al.,
>>>>
>>>> We are seeing strange behavior with gMinuit. It seems to come and go. I
>>>> expect it to be there after I do it fit.
>>>>
>>>> An example:
>>>>
>>>> I have a histogram (it doesn't matter what it is).
>>>>
>>>> root [26] h->Fit("pol4")
>>>> Fitting results:
>>>> Parameters:
>>>> NO. VALUE ERROR
>>>> 0 2.625170e+03 1.191186e+02
>>>> 1 -1.565262e+04 1.055977e+03
>>>> 2 3.861477e+04 3.327115e+03
>>>> 3 -4.315887e+04 4.446220e+03
>>>> 4 1.804345e+04 2.140152e+03
>>>> (Int_t)0
>>>> root [27] gMinuit
>>>> (class TMinuit*)0x0
>>>> root [28]
>>>>
>>>> -->gMinuit is MIA
>>>>
>>>> root [28] h->Fit("gaus")
>>>> FCN=687.968 FROM MIGRAD STATUS=CONVERGED 3927 CALLS 3928
>>>> TOTAL
>>>> EDM=5.19353e-06 STRATEGY= 1 ERR MATRIX NOT
>>>> POS-DEF
>>>> EXT PARAMETER APPROXIMATE STEP FIRST
>>>> NO. NAME VALUE ERROR SIZE DERIVATIVE
>>>> 1 Constant 1.93812e+09 1.54608e+08 9.24169e+02 2.24749e-10
>>>> 2 Mean -8.98813e+00 2.37909e-02 2.18708e-05 1.46725e+00
>>>> 3 Sigma 1.67356e+00 3.02321e-02 2.53915e-03** at limit **
>>>> (Int_t)0
>>>> root [29] gMinuit
>>>> (class TMinuit*)0x9486650
>>>>
>>>> -->gMinuit is there!
>>>>
>>>> In a more complex sitution where we construct a simple TF1 in a macro,
>>>> gMinuit is sometimes there and sometimes not -- seemingly w/o reason --
>>>>
>>>> -Art S.
>>>>
>>>>
>>>>
>>>> A.E. Snyder, Group EC \!c*p?/
>>>> SLAC Mail Stop #95 ((. .))
>>>> Box 4349 |
>>>> Stanford, Ca, USA, 94309 '\|/`
>>>> e-mail:snyder_at_slac.stanford.edu o
>>>> phone:650-926-2701 _
>>>> http://www.slac.stanford.edu/~snyder BaBar
>>>> FAX:650-926-2657 Collaboration
>>>>
>>>>
>>>>
>>>
>>>
>>
>
>
Received on Tue Jun 16 2009 - 02:05:00 CEST

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