Re: Accessing TFx parameters by name

From: Eric Vaandering <ewv_at_fnal.gov>
Date: Wed, 09 Mar 2005 14:18:56 -0600

This is what I get with root 4.02/00 while GetParameter rather than GetParError works find. Am I doing something wrong?

root [0] TF1 *P1G = new
TF1("P1G","[0]+[1]*x+0.005*[2]*exp(-0.5*pow(((x-[3])/[4]),2))/(2.507*[4])");

root [1] P1G -> SetParName(2,"Yield");
root [2] cout << P1G -> GetParError(2);
root [3] cout << P1G -> GetParError("Yield");

Error: Can't call TF1::GetParError("Yield") in current scope FILE:(tmpfile) LINE:1 Possible candidates are...

filename       line:size busy function type and name  (in TF1)
(compiled)        0:0    0 public: virtual Double_t GetParError(Int_t ipar) const;
filename       line:size busy function type and name  (in TFormula)
filename       line:size busy function type and name  (in TNamed)
filename       line:size busy function type and name  (in TObject)
filename       line:size busy function type and name  (in TAttLine)
filename       line:size busy function type and name  (in TAttFill)
filename       line:size busy function type and name  (in TAttMarker)

*** Interpreter error recovered ***

Rene BRUN wrote:
> Eric
>
> You can acall GetParameter and GetParError on a TF1,2,3.
>
> You call FixParameter, ReleaseParameter in the TVirtualFitter
> interface or derived classes.
>
> Rene Brun
>
> On Wed, 9 Mar
> 2005, Eric Vaandering wrote:
>
>

>>I'm using root 3.10, but it seems root v4 has the same issue.
>>
>>One can call SetParameter("name",value) on a TF1 for instance but not call
>>GetParError, FixParameter, or ReleaseParameter the same way since TFormula
>>doesn't provide those methods
>>
>>Is there a reason for this or can such a method be added in future releases.
>>
>>Thanks,
>>
>>Eric Vaandering
>>
>>


-- 
Eric Vaandering           Phone: 615-343-6599     FAX: 615-343-7217

  Vanderbilt University Email: ewv_at_fnal.gov   Department of Physics http://www.hep.vanderbilt.edu/~vondo

---

If you had your life to live over again- you'd need more money.

                                 -Construction Digest
______________________________________________________________________________

Therapy is expensive, poppin' bubble wrap is cheap! You choose. Received on Wed Mar 09 2005 - 21:26:02 MET