THnSparse::Add() does not preserve weights #11333
Description
Describe the bug
When adding two histograms, the weights associated with the bin contents of those histograms should also be added appropriately. THnSparse does not do this. It still reports the weights of the first histogram, ignoring the second.
Expected behavior
The sum of weights should include the weights of both histograms that were added together.
To Reproduce
The script is here: https://www.dropbox.com/s/j5wvixrmdtdx3b5/testTHNadd.C?dl=0
(GitHub apparently does not allow attaching .C files)
root -b -l -q testTHNadd.CThis script shows the bug by comparing two cases:
- Filling one histogram twice
- Filling two histograms once and adding them
The output is:
THnSparseT<TArrayD> (*0x6c127c0): "hs" "CASE 1"
8 dimensions, 2 entries in 2 filled bins
axis 0 "": 10 bins (-5..10), variable bin sizes
axis 1 "": 10 bins (-10..70), variable bin sizes
axis 2 "": 5 bins (-1000..3000), variable bin sizes
axis 3 "": 30 bins (-3..3), variable bin sizes
axis 4 "": 10 bins (0..5), variable bin sizes
axis 5 "": 4 bins (0..2), variable bin sizes
axis 6 "": 18 bins (0..2), variable bin sizes
axis 7 "": 12 bins (0..5), variable bin sizes
with error calculation
Sum(w)=2, Sum(w^2)=2.5
axis 0: Sum(w*x)=3.5, Sum(w*x^2)=6.5
axis 1: Sum(w*x)=3.5, Sum(w*x^2)=6.5
axis 2: Sum(w*x)=3.5, Sum(w*x^2)=6.5
axis 3: Sum(w*x)=3.5, Sum(w*x^2)=6.5
axis 4: Sum(w*x)=3.5, Sum(w*x^2)=6.5
axis 5: Sum(w*x)=3.5, Sum(w*x^2)=6.5
axis 6: Sum(w*x)=3.5, Sum(w*x^2)=6.5
axis 7: Sum(w*x)=3.5, Sum(w*x^2)=6.5
coordinates stored in 1 chunks of 16384 entries
3.07559e-09 of bins filled using 6.61576e-05 of memory compared to an array
Bin at (5,2,2,21,3,3,10,3) = 0.5 (+/- 0.5)
Bin at (5,2,2,26,5,5,19,5) = 1.5 (+/- 1.5)
2
THnSparseT<TArrayD> (*0x57c3b10): "hs" "CASE 2"
8 dimensions, 2 entries in 2 filled bins
axis 0 "": 10 bins (-5..10), variable bin sizes
axis 1 "": 10 bins (-10..70), variable bin sizes
axis 2 "": 5 bins (-1000..3000), variable bin sizes
axis 3 "": 30 bins (-3..3), variable bin sizes
axis 4 "": 10 bins (0..5), variable bin sizes
axis 5 "": 4 bins (0..2), variable bin sizes
axis 6 "": 18 bins (0..2), variable bin sizes
axis 7 "": 12 bins (0..5), variable bin sizes
with error calculation
Sum(w)=0.5, Sum(w^2)=0.25
axis 0: Sum(w*x)=0.5, Sum(w*x^2)=0.5
axis 1: Sum(w*x)=0.5, Sum(w*x^2)=0.5
axis 2: Sum(w*x)=0.5, Sum(w*x^2)=0.5
axis 3: Sum(w*x)=0.5, Sum(w*x^2)=0.5
axis 4: Sum(w*x)=0.5, Sum(w*x^2)=0.5
axis 5: Sum(w*x)=0.5, Sum(w*x^2)=0.5
axis 6: Sum(w*x)=0.5, Sum(w*x^2)=0.5
axis 7: Sum(w*x)=0.5, Sum(w*x^2)=0.5
coordinates stored in 1 chunks of 16384 entries
3.07559e-09 of bins filled using 6.61576e-05 of memory compared to an array
Bin at (5,2,2,21,3,3,10,3) = 0.5 (+/- 0.5)
Bin at (5,2,2,26,5,5,19,5) = 1.5 (+/- 1.5)
0.5
Setup
- ROOT versions: tested 6.06.00, 6.12.07, 6.24.07 (all have the bug)
- Scientific Linux 7.9, AlmaLinux 8.6
- From CMSSW on cvmfs