updating FitSlicesY histograms

From: Wuyi Liu (liu@nevis1.nevis.columbia.edu)
Date: Sat Oct 02 1999 - 04:28:40 MEST


Hi, the function FitSlicesY has simplied quite some coding for me.  But I
have problem updating the resulting histograms.  Here is what I did:

root [1] TTree *TLQ=(TTree*)LQ->Get("h10");
root [2] TH2F *energy=new TH2F("energy","",25,0,500,160,-1,1);
root [3] TLQ->Draw("(pe[3]-epe[0])/epe[0]:pe[3]>>energy","Ejetc[0]>100");
Warning in <MakeDefCanvas>: creating a default canvas with name c1
root [5] energy->FitSlicesY()
root [6] energy_1->Draw()  //draw the mean of each slices

so far everything is fine.  Now I want to remove the cut when projecting
into the histogram.  Simply do:

	TLQ->Draw("(pe[3]-epe[0])/epe[0]:pe[3]>>energy","");
	energy->FitSlicesY()
	energy_1->Draw()

and I obtained the identical energy_1 as before, ie, I did not get root to
be awrare of the updated energy_1.  Then I tried to delete all the
histograms in the following order:

	delete energy
	delete energy_0
	delete energy_1
	delete energy_2
	delete energy_chi2

and I try to make the new histogram again:

	TLQ->Draw("(pe[3]-epe[0])/epe[0]:pe[3]>>energy","");
	energy->FitSlicesY()
	energy_1->Draw()
Error: No symbol energy_1->Draw() in current scope FILE:/var/tmp/zaaa030JK
LINE:1

If, when deleting all the energy's histograms, I delete energy in the
last:

        delete energy_0
        delete energy_1
        delete energy_2
        delete energy_chi2
        delete energy

and then try to make the new histogram again:

        TLQ->Draw("(pe[3]-epe[0])/epe[0]:pe[3]>>energy","");
        energy->FitSlicesY()
        energy_1->Draw()

 *** Break *** segmentation violation


May I know what I missed?

Best regards, Wuyi



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