[tmva][sofie] Enhance Softplus stability in ROperator_BasicUnary#21092
Open
AdityaDRathore wants to merge 1 commit intoroot-project:masterfrom
Open
[tmva][sofie] Enhance Softplus stability in ROperator_BasicUnary#21092AdityaDRathore wants to merge 1 commit intoroot-project:masterfrom
AdityaDRathore wants to merge 1 commit intoroot-project:masterfrom
Conversation
This commit specializes the `UnaryOpTraits` for `kSoftplus` within `ROperator_BasicUnary` to address numerical instability issues (Issue root-project#21071). Changes: - Implemented exact hexfloat thresholding (0x1.4p+4f) to prevent overflow for inputs > 20.0. - Replaced `std::log(std::exp(x)+1)` with `std::log1p(std::exp(x))` to preserve precision for negative inputs. - Validated via dedicated `TestSofieSoftplus` suite unit testing overflow and bit-exact generation. Fixes root-project#21071
This was referenced Feb 1, 2026
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
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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
This PR implements numerical stability improvements for the
Softplusoperator, addressing overflow issues identified in Issue #21071.It supersedes PR #21023 (which was closed due to branch history alignment).
Changes
0x1.4p+4f(20.0f) to preventexp()overflow for large inputs.log(exp(x)+1)withstd::log1p(std::exp(x))to preserve precision for negative inputs.TestSofieSoftplus.cxxverifying bit-exact hexfloat emission and overflow protection.Technical Context
ROperator_BasicUnary(viaUnaryOpTraitsspecialization).Fixes #21071
cc: @sanjibansg @lmoneta @bellenot