Fix Chi2Test: Support residuals for 2D/3D histograms #20798
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Fixed bug where Chi2Test only stored residuals for 1D histograms. For 2D/3D histograms, the residual array indexing ignored j and k loop indices, causing incorrect storage. Added resIndex counter for each comparison mode (UU, UW, WW) to properly index the residuals array for multi-dimensional histograms. Fixes root-project#20761
hageboeck
reviewed
Jan 7, 2026
Member
hageboeck
left a comment
hageboeck
left a comment
There was a problem hiding this comment.
Hello, thanks for the contribution!
I think we could remove two unnecessary if (res). Please have a look if you agree.
Co-authored-by: Stephan Hageboeck <[email protected]>
Removed redundant if(res) checks Co-authored-by: Stephan Hageboeck <[email protected]>
Test Results 21 files 21 suites 3d 14h 17m 32s ⏱️ Results for commit f6053e7. |
dpiparo
pushed a commit
to dpiparo/root
that referenced
this pull request
Jan 11, 2026
) [hist] Chi2Test: Support residuals for 2D/3D histograms Fixed bug where Chi2Test only stored residuals for 1D histograms. For 2D/3D histograms, the residual array indexing ignored j and k loop indices, causing incorrect storage. Added resIndex counter for each comparison mode (UU, UW, WW) to properly index the residuals array for multi-dimensional histograms. Fixes root-project#20761 (cherry picked from commit 5b770f8)
dpiparo
pushed a commit
to dpiparo/root
that referenced
this pull request
Jan 11, 2026
) [hist] Chi2Test: Support residuals for 2D/3D histograms Fixed bug where Chi2Test only stored residuals for 1D histograms. For 2D/3D histograms, the residual array indexing ignored j and k loop indices, causing incorrect storage. Added resIndex counter for each comparison mode (UU, UW, WW) to properly index the residuals array for multi-dimensional histograms. Fixes root-project#20761 (cherry picked from commit 5b770f8)
dpiparo
pushed a commit
that referenced
this pull request
Jan 11, 2026
[hist] Chi2Test: Support residuals for 2D/3D histograms Fixed bug where Chi2Test only stored residuals for 1D histograms. For 2D/3D histograms, the residual array indexing ignored j and k loop indices, causing incorrect storage. Added resIndex counter for each comparison mode (UU, UW, WW) to properly index the residuals array for multi-dimensional histograms. Fixes #20761 (cherry picked from commit 5b770f8)
dpiparo
pushed a commit
that referenced
this pull request
Jan 12, 2026
[hist] Chi2Test: Support residuals for 2D/3D histograms Fixed bug where Chi2Test only stored residuals for 1D histograms. For 2D/3D histograms, the residual array indexing ignored j and k loop indices, causing incorrect storage. Added resIndex counter for each comparison mode (UU, UW, WW) to properly index the residuals array for multi-dimensional histograms. Fixes #20761 (cherry picked from commit 5b770f8)
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Description
Fixes #20761
This PR fixes a bug in
TH1::Chi2TestXwhere residuals were only correctly stored for 1D histograms. For 2D and 3D histograms, the residual array indexing only used theiloop index and ignoredjandk, causing incorrect storage.Changes
resIndexcounter for each of the three comparison modes (UU, UW, WW)res[i - i_start]withres[resIndex]in all three sectionsresIndex++increment after each residual is storedTesting
The fix ensures that residuals are stored sequentially for all bins in 2D/3D histograms, matching the order returned by
GetBin(i, j, k).Impact
Users can now retrieve residuals from
Chi2Testfor 2D and 3D histograms as originally intended by passing a residuals array.