RE: Can't fix sigma in gaus ...

From: Snyder, Arthur E. <snyder_at_slac.stanford.edu>
Date: Wed, 27 Jun 2012 19:48:40 -0700

Is roottalk back? Is anybody reading it?

I guess thre may be quite a back log ...

-AE

---

From: Arthur E. Snyder [snyder_at_slac.stanford.edu] Sent: Tuesday, June 26, 2012 3:41 PM
To: Snyder, Arthur E.
Cc: roottalk_at_root.cern.ch
Subject: Can't fix sigma in gaus ...

I find I can't fix |sigma| in function 'gaus'

root [3] fgau->FixParameter(2,1)
root [4] fgau->Print()

                  gaus : gaus Ndim= 1, Npar= 3, Noper= 1

  fExpr[0] = gaus action = 110 action param = 0 Optimized expression

  fExpr[0] = gaus                  action = 110 action param = 0
  Par  0              Constant = 1
  Par  1                  Mean = 0
  Par  2                 Sigma = 1
root [5] hSignif->Draw()

root [6] hSignif->SetAxisRange(-4,4)
root [7] hSignif->Fit(fgau)
  FCN=43.6279 FROM MIGRAD STATUS=CONVERGED 68 CALLS 69 TOTAL

                      EDM=4.24208e-13    STRATEGY= 1  ERROR MATRIX
UNCERTAINTY   2.2 per cent
   EXT PARAMETER                                   STEP         FIRST
   NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE
    1  Constant     5.51347e+00   6.30205e-01   8.36689e-05  -2.02569e-06
    2  Mean        -1.13119e-01   1.17954e-01  -8.33876e-06   6.14754e-06
    3  Sigma        1.23109e+00   1.39661e-01  -2.78385e-06  -1.57846e-05

(class TFitResultPtr)174529088

--FixParameter works for |Constant| and |mean|

--That does not seem right! A bug? Hard to believe it would not have
noticed previouly though --

????

-AE

A.E. Snyder, The Former Group C (TFC)        \!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:707-313-0250                          Collaboration
                                                 &
                                            Fermi/GLAST

Received on Thu Jun 28 2012 - 04:49:58 CEST