TF1 cloning problem (correctiong subject)

> Hi Rooters,
>
> I find the following weird behavior with cloned |TF1|s:
>
> fp=makePowerLaw(); <---creates a simple power law TF1
>
> make function: lo=1 up=10 power=2 name=powerLaw
> (class TF1*)0xa0f6ad0
>
> root [29] fp->Print()
> powerLaw : Ndim= 1, Npar= 4, Noper= 0
> Par 0 p0 = 1
> Par 1 p1 = 2
> Par 2 p2 = 1
> Par 3 p3 = 10
> root [30]
>
> root [30] fpa=(TF1*)fp->Clone()
> (class TF1*)0xa0f6968
>
> root [32] fpa->Print()
> powerLaw : Ndim= 1, Npar= 4, Noper= 0
> Par 0 p0 = 1
> Par 1 p1 = 2
> Par 2 p2 = 1
> Par 3 p3 = 10
>
>
> root [31] fpa->Draw()
> root [32]
>
> --at this point cloned copy makes same plot as original |fp|
>
> root [6] fpa->SetParameter(1,4)
> root [7] fpa->Print()
> powerLaw : Ndim= 1, Npar= 4, Noper= 0
> Par 0 p0 = 1
> Par 1 p1 = 4
> Par 2 p2 = 1
> Par 3 p3 = 10
>
> --changing parameter of clone seems to work, but ..
>
> root [8] fpa->Draw() <--- attached looks the same as fp->Draw() with p1=2!
>
> but the plot still shows the same as above .. i.e., p1=2, not 4
>
> If I look with debugger this:
>
> (gdb) b 'powerLaw(double*, double*)'
> Breakpoint 1 at 0x4b8feb2: file
> /afs/slac.stanford.edu/u/ek/snyder/glast/root/./powerLaw.C, line 10.
> (gdb) c
>
> I find |fpa->Draw()| does not stop in the underlying c++ function
> |PowerLaw|.
>
> |fp| does stop in |PowerLaw|
>
> This is pretty strange. A clone is not a clone. It's behavior is not the
> same as the function i was cloned from. It seems to have somekind of copy
> of the curve, but no control over it.
>
> If I try to fit with clone, it fails.
>
> Is this a bug or a feature?
>
> -Arthur
>
>
> powerLaw:
>
> double powerLaw(double* x,double *par) {
>
> double N=par[0];
> double power=par[1];
> double xp=x[0];
>
>
> double emin=par[2];
> double emax=par[3];
>
> if(xp<=0) return 0.0;
>
> double temp=1.0/TMath::Power(xp,power);
>
> double fIntegral=
>
> (TMath::Power((emin),(-power+1))-TMath::Power((emax),(-power+1)))/(power-1);
>
> temp/=fIntegral;
> temp*=N;
>
> return temp;
> }
>
>
>
> 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
>
>
>
> On Tue, 12 Jun 2012, Chris Jones wrote:
>
>
> [NON-Text Body part not included]
Received on Tue Jun 12 2012 - 22:53:50 CEST