Problem with getV1()

ROOT
1

I am wondering why my two vectors m1 and m2 are different in the following two cases

  1. t1->Draw(“mass[0]:mass[1]:factor”,oSNR_cut,“goff”);
    double* m2=t1->GetV1();
    double* m1=t1->GetV2();

  2. t1->Draw(“mass[0]:mass[1]:factor”,wave_cuts,“goff”);
    double* m2=t1->GetV1();
    double* m1=t1->GetV2();
    -----some code
    t1->Draw(“mass[0]:mass[1]:factor”,oSNR_cut,“goff”);
    double* m2=t1->GetV1();
    double* m1=t1->GetV2();

I was wondering shouldn’t in case (2) the second draw overwrite the first draw and will reproduce case (1). Please help me understand.

regards,
Vaibhav

2

actually its this line which is causing problem
t1->SetEstimate(t1->GetEntries(wave_cuts))

To reiterate

  1. t1->Draw(“mass[0]:mass[1]:factor”,oSNR_cut,“goff”);
    and
  2. t1->Draw(“mass[0]:mass[1]:factor”,wave_cuts,“goff”);
    t1->Draw(“mass[0]:mass[1]:factor”,oSNR_cut,“goff”);

produce the same result for (1) and (2)

but
t1->SetEstimate(t1->GetEntries(wave_cuts))

  1. t1->Draw(“mass[0]:mass[1]:factor”,oSNR_cut,“goff”);
    and
  2. t1->Draw(“mass[0]:mass[1]:factor”,wave_cuts,“goff”);
    t1->Draw(“mass[0]:mass[1]:factor”,oSNR_cut,“goff”);

(1) and (2) do not produce the same results

3

Hi,

See void TTree::SetEstimate(Long64_t n /* = 1000000 */) { // Set number of entries to estimate variable limits. // If n is -1, the estimate is set to be the current maximum // for the tree (i.e. GetEntries() + 1) // If n is less than -1, the behavior is undefined. Setting to only GetEntries() pose some boundary issues.

Philippe.