TGraph2D::Fit doesn't return

From: Sébastien <blinkseb_at_gmail.com>
Date: Fri, 9 Apr 2010 23:10:48 +0200

Root 2.06/00b
Linux x86

Good evening,

First step with ROOT, I'm trying to fit some data for my school project. I'm using ROOT within my c++ app.

I'm using a TGraph2D, filled with points using the TGraph2D::SetPoint method. The graph render well when I call the Draw() function. It's a graph of 400x400 points.

I try to fit the TGraph2D by a 2D Gaussian, like that :

TF2 formula("gaus2d", Gaus2D, 0, 400, 0, 400, 5); formula.SetParameters(255, 200, 200, 200, 200); formula.SetParNames("Const","X_{0}","#sigma_{x}", "Y_{0}","#sigma_{y}");

graph->Fit(formula.c_str(), "SVR");

(Obviously, graph is a TGraph2D variable)

The fit works well, I can see the output on the console (verbose on), but, when the fit converged, the app freeze. I've the following on my console :

FCN=2040.94 FROM MIGRAD    STATUS=CONVERGED    1161 CALLS        1162 TOTAL
  EDM=1.31725e-10    STRATEGY= 1      ERROR MATRIX ACCURATE
   EXT PARAMETER                                   STEP         FIRST
   NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE
    1  Const        2.54956e+02   5.05628e-02   7.90304e-04  -9.42453e-05
    2  X_{0}        2.00000e+02   3.12950e-03   9.53674e-05  -3.34396e-03
    3  #sigma_{x}   1.57515e+01   3.12097e-03   5.62767e-05  -5.08722e-04
    4  Y_{0}        2.00000e+02   3.12950e-03   9.53674e-05   1.03130e-03

    5 #sigma_{y} 1.57515e+01 3.12097e-03 5.62767e-05 2.91193e-03   EXTERNAL ERROR MATRIX. NDIM= 25 NPAR= 5 ERR DEF=1

   2.557e-03 -4.742e-10 -7.869e-05 -4.748e-10 -7.869e-05


  -4.742e-10  9.794e-06  2.919e-11  1.008e-13 -2.210e-14

  -7.869e-05  2.919e-11  9.740e-06 -2.060e-14 -1.764e-08

-4.748e-10 1.008e-13 -2.060e-14 9.794e-06 2.933e-11
-7.869e-05 -2.210e-14 -1.764e-08 2.933e-11 9.740e-06
  PARAMETER CORRELATION COEFFICIENTS

        NO.  GLOBAL      1      2      3      4      5
         1  0.70582   1.000 -0.000 -0.499 -0.000 -0.499
         2  0.00000  -0.000  1.000  0.000  0.000 -0.000
         3  0.57630  -0.499  0.000  1.000 -0.000 -0.002
         4  0.00000  -0.000  0.000 -0.000  1.000  0.000
         5  0.57630  -0.499 -0.000 -0.002  0.000  1.000

  EXTERNAL ERROR MATRIX. NDIM= 5 NPAR= 5 ERR DEF=1

   2.557e-03 -4.742e-10 -7.869e-05 -4.748e-10 -7.869e-05


  -4.742e-10  9.794e-06  2.919e-11  1.008e-13 -2.210e-14

  -7.869e-05  2.919e-11  9.740e-06 -2.060e-14 -1.764e-08

-4.748e-10 1.008e-13 -2.060e-14 9.794e-06 2.933e-11
-7.869e-05 -2.210e-14 -1.764e-08 2.933e-11 9.740e-06

And nothing more, I have to kill the app...

It works fine if I use a 40x40 points graph, but I need a 400x400, and maybe even more.

Is there something I've made wrong?

Thanks for your answer.

-- 
Sébastien Brochet
Master 1 Physique - Université Lyon 1
sebastien.brochet_at_etu.univ-lyon1.fr

Received on Fri Apr 09 2010 - 23:11:06 CEST