ERGO-Code/HiGHS
Nov 2024 – Jan 2026
15 Months active
Languages Used
C++MPSCtextLP
Technical Skills
Algorithm DevelopmentAlgorithm OptimizationAlgorithm RefactoringBug FixingC++C++ Development
fwesselm
PROFILE
Fwesselm
Frank Wessels contributed to the ERGO-Code/HiGHS repository, focusing on developing and refining core solver features for large-scale linear and mixed-integer programming. Over 15 months, he enhanced presolve logic, cut generation, and numerical stability, addressing edge cases and improving solution reliability. His work involved deep algorithmic development and optimization in C and C++, with careful attention to code readability, maintainability, and performance. Frank introduced robust testing, memory management improvements, and modernized API structures, ensuring safer and faster solves. By integrating advanced mathematical modeling and debugging practices, he delivered a more stable, extensible solver platform for enterprise optimization workloads.
Overall Statistics
Feature vs Bugs
65%Features
Repository Contributions
497Total
Bugs
78
Commits
497
Features
144
Lines of code
46,899
Activity Months15
Your Network
46 people
Work History
January 2026
21 Commits • 5 Features
Jan 1, 2026January 2026 performance summary for ERGO-Code/HiGHS. Delivered focused performance and correctness improvements across memory management, column typing, and code quality, with an emphasis on business value and solver reliability. Key outcomes include memory and pre-allocation improvements that reduce allocations and accelerate solution phases, comprehensive column handling correctness improvements using tolerance and absolute value checks via new utilities, and targeted refactors to improve readability and maintainability. Added functionality to check whether a set of variables forms a clique in the graph, contributing to stronger graph-based validations. Code modernization efforts included replacing C-style casts with C++-style static_cast to improve type safety, coupled with typos/documentation cleanup to boost maintainability. Overall impact includes faster, more stable solves, safer code changes, and clearer engineering momentum for future iterations.
21 Commits • 5 Features
Jan 1, 2026January 2026 performance summary for ERGO-Code/HiGHS. Delivered focused performance and correctness improvements across memory management, column typing, and code quality, with an emphasis on business value and solver reliability. Key outcomes include memory and pre-allocation improvements that reduce allocations and accelerate solution phases, comprehensive column handling correctness improvements using tolerance and absolute value checks via new utilities, and targeted refactors to improve readability and maintainability. Added functionality to check whether a set of variables forms a clique in the graph, contributing to stronger graph-based validations. Code modernization efforts included replacing C-style casts with C++-style static_cast to improve type safety, coupled with typos/documentation cleanup to boost maintainability. Overall impact includes faster, more stable solves, safer code changes, and clearer engineering momentum for future iterations.
January 2026
December 2025
68 Commits • 25 Features
Dec 1, 2025December 2025 — ERGO-Code/HiGHS: Consolidated reliability, performance, and maintainability improvements with a solid foundation for the 2026 release. Batch 1 work shows strong momentum with several in-flight commits still maturing, while key features and hardening efforts were delivered and stabilized to reduce risk and improve user value.
December 2025
68 Commits • 25 Features
Dec 1, 2025December 2025 — ERGO-Code/HiGHS: Consolidated reliability, performance, and maintainability improvements with a solid foundation for the 2026 release. Batch 1 work shows strong momentum with several in-flight commits still maturing, while key features and hardening efforts were delivered and stabilized to reduce risk and improve user value.
November 2025
25 Commits • 10 Features
Nov 1, 2025November 2025 — ERGO-Code/HiGHS: Delivered a set of feature enhancements, reliability fixes, and maintainability improvements. Key work included a rename operation to reflect updated identifiers, stopping criteria tuning with centering groundwork for analytic center computation, and dynamic tolerance scaling to improve robustness across diverse problems. Added solver integration support via a new model file, introduced a lower bound change utility, and provided a configurable option to control cut separation at nodes. A targeted refactor of HighsRedcostFixing::addRootRedcost enhanced readability and future maintainability. In addition, tests were added to validate updated behavior and regression coverage, complemented by minor refactors to improve code quality. Overall, these changes strengthen numerical accuracy, stability, and performance, enabling more reliable optimization and quicker iteration cycles.
25 Commits • 10 Features
Nov 1, 2025November 2025 — ERGO-Code/HiGHS: Delivered a set of feature enhancements, reliability fixes, and maintainability improvements. Key work included a rename operation to reflect updated identifiers, stopping criteria tuning with centering groundwork for analytic center computation, and dynamic tolerance scaling to improve robustness across diverse problems. Added solver integration support via a new model file, introduced a lower bound change utility, and provided a configurable option to control cut separation at nodes. A targeted refactor of HighsRedcostFixing::addRootRedcost enhanced readability and future maintainability. In addition, tests were added to validate updated behavior and regression coverage, complemented by minor refactors to improve code quality. Overall, these changes strengthen numerical accuracy, stability, and performance, enabling more reliable optimization and quicker iteration cycles.
November 2025
October 2025
60 Commits • 21 Features
Oct 1, 20252025-10 monthly performance summary for ERGO-Code/HiGHS focusing on delivering robust numerical analysis, code quality, and observability improvements. The team concentrated on hardening bound analysis, tightening bounds with clique-awareness, and improving safety and maintainability, while expanding debugging support and documentation.
October 2025
60 Commits • 21 Features
Oct 1, 20252025-10 monthly performance summary for ERGO-Code/HiGHS focusing on delivering robust numerical analysis, code quality, and observability improvements. The team concentrated on hardening bound analysis, tightening bounds with clique-awareness, and improving safety and maintainability, while expanding debugging support and documentation.
September 2025
64 Commits • 20 Features
Sep 1, 2025Month: 2025-09 HiGHS development—delivered core features, improved stability, and refactoring for maintainability. Focused on solver capability enhancements, code quality, and test coverage to enable faster, safer releases and clearer business value.
64 Commits • 20 Features
Sep 1, 2025Month: 2025-09 HiGHS development—delivered core features, improved stability, and refactoring for maintainability. Focused on solver capability enhancements, code quality, and test coverage to enable faster, safer releases and clearer business value.
September 2025
August 2025
41 Commits • 11 Features
Aug 1, 2025August 2025 for ERGO-Code/HiGHS: Stabilized core behavior through critical bug fixes and test fixes; expanded test coverage for binary variables; introduced calcMaxVarBounds to support robust maximum-bound calculations; and implemented broad code quality improvements including documentation, readability enhancements, and lambda-related integration/cleanup. These efforts reduce regression risk, improve maintainability, and position HiGHS for more reliable feature delivery.
August 2025
41 Commits • 11 Features
Aug 1, 2025August 2025 for ERGO-Code/HiGHS: Stabilized core behavior through critical bug fixes and test fixes; expanded test coverage for binary variables; introduced calcMaxVarBounds to support robust maximum-bound calculations; and implemented broad code quality improvements including documentation, readability enhancements, and lambda-related integration/cleanup. These efforts reduce regression risk, improve maintainability, and position HiGHS for more reliable feature delivery.
July 2025
16 Commits • 1 Features
Jul 1, 2025In July 2025, delivered a focused Presolve Robustness and Refactor (HPresolve) enhancement for ERGO-Code/HiGHS, improving correctness, logging accuracy, bound handling, and readability. Implemented new helper utilities, standardized lambda naming, and expanded test coverage to strengthen presolve reliability and maintainability. The work reduces risk in LP reductions, improves traceability through better logging, and lays groundwork for future optimizations in presolve.
16 Commits • 1 Features
Jul 1, 2025In July 2025, delivered a focused Presolve Robustness and Refactor (HPresolve) enhancement for ERGO-Code/HiGHS, improving correctness, logging accuracy, bound handling, and readability. Implemented new helper utilities, standardized lambda naming, and expanded test coverage to strengthen presolve reliability and maintainability. The work reduces risk in LP reductions, improves traceability through better logging, and lays groundwork for future optimizations in presolve.
July 2025
June 2025
47 Commits • 11 Features
Jun 1, 2025June 2025 (ERGO-Code/HiGHS): Delivered core feature refinements, stability hardening, and new capabilities. Key work focused on cleaning up and hardening the merging of variables and detection logic for parallel rows/columns, with updates to changeColLower and changeColUpper. Expanded the test suite and cleaned up tests to improve coverage and regression safety. Implemented critical correctness fixes in HPresolve components (infeasibility checks for isImpliedInteger and sparsify) and addressed issues related to weak domination, header integrity, and formatting. Added readability and maintainability improvements (range-based loops, const-correctness enhancements, and identifier/name fixes). Introduced new functionality with the Chaser feature and added an operator to broaden capabilities.
June 2025
47 Commits • 11 Features
Jun 1, 2025June 2025 (ERGO-Code/HiGHS): Delivered core feature refinements, stability hardening, and new capabilities. Key work focused on cleaning up and hardening the merging of variables and detection logic for parallel rows/columns, with updates to changeColLower and changeColUpper. Expanded the test suite and cleaned up tests to improve coverage and regression safety. Implemented critical correctness fixes in HPresolve components (infeasibility checks for isImpliedInteger and sparsify) and addressed issues related to weak domination, header integrity, and formatting. Added readability and maintainability improvements (range-based loops, const-correctness enhancements, and identifier/name fixes). Introduced new functionality with the Chaser feature and added an operator to broaden capabilities.
May 2025
2 Commits • 2 Features
May 1, 2025May 2025: Enhanced HiGHS HPresolve robustness and regression coverage. Key outcomes include (1) tolerance-based forcing-row detection with scaling by minAbsCoef and relative tolerance, improving stability across problem instances; (2) a new regression test for issue-2290 (MI problem) with an MPS MI instance and a C++ test verifying the optimal objective. No major bugs fixed this month; focus was on feature refinements and test coverage to reduce future risk. Business value centers on reliability, predictability of solutions, and stronger regression safeguards.
2 Commits • 2 Features
May 1, 2025May 2025: Enhanced HiGHS HPresolve robustness and regression coverage. Key outcomes include (1) tolerance-based forcing-row detection with scaling by minAbsCoef and relative tolerance, improving stability across problem instances; (2) a new regression test for issue-2290 (MI problem) with an MPS MI instance and a C++ test verifying the optimal objective. No major bugs fixed this month; focus was on feature refinements and test coverage to reduce future risk. Business value centers on reliability, predictability of solutions, and stronger regression safeguards.
May 2025
April 2025
13 Commits • 3 Features
Apr 1, 2025For 2025-04 (ERGO-Code/HiGHS), a concise monthly contribution focused on improving heuristic reliability, consistency, and presolve robustness. The work delivers cleaner, better-performing components with higher maintainability and clear future scalability.
April 2025
13 Commits • 3 Features
Apr 1, 2025For 2025-04 (ERGO-Code/HiGHS), a concise monthly contribution focused on improving heuristic reliability, consistency, and presolve robustness. The work delivers cleaner, better-performing components with higher maintainability and clear future scalability.
March 2025
38 Commits • 12 Features
Mar 1, 2025March 2025: Delivered targeted bug fixes, refactors, and validation work in HiGHS to improve robustness, maintainability, and solver performance. The month focused on stabilizing infeasibility handling, enhancing the lifting logic, expanding test coverage, and improving code quality for quicker future evolution.
38 Commits • 12 Features
Mar 1, 2025March 2025: Delivered targeted bug fixes, refactors, and validation work in HiGHS to improve robustness, maintainability, and solver performance. The month focused on stabilizing infeasibility handling, enhancing the lifting logic, expanding test coverage, and improving code quality for quicker future evolution.
March 2025
February 2025
50 Commits • 16 Features
Feb 1, 2025February 2025 — HiGHS (ERGO-Code/HiGHS) focused on strengthening solver correctness, stability, and maintainability, with enhancements to presolve, HPresolve, and observability. Key features delivered include: row presolve integration to reduce problem size and improve conditioning; significant HPresolve::transformColumn improvements for correctness, reduced rounding, and performance gains; a Lambda-based refactor within HPresolve to modernize the codebase and simplify maintenance; presolve improvements with an option to disable presolve and ensuring proper basis handling when presolve is unused, along with accompanying tests; and expanded test coverage plus application logging to improve observability and reliability across deployments.
February 2025
50 Commits • 16 Features
Feb 1, 2025February 2025 — HiGHS (ERGO-Code/HiGHS) focused on strengthening solver correctness, stability, and maintainability, with enhancements to presolve, HPresolve, and observability. Key features delivered include: row presolve integration to reduce problem size and improve conditioning; significant HPresolve::transformColumn improvements for correctness, reduced rounding, and performance gains; a Lambda-based refactor within HPresolve to modernize the codebase and simplify maintenance; presolve improvements with an option to disable presolve and ensuring proper basis handling when presolve is unused, along with accompanying tests; and expanded test coverage plus application logging to improve observability and reliability across deployments.
January 2025
17 Commits • 2 Features
Jan 1, 2025January 2025 monthly summary for ERGO-Code/HiGHS. Focused on robustness, correctness, and performance improvements across presolve, MIP timing/logging, and solver core. Delivered key features and fixes with measurable business value in reliability, speed, and maintainability.
17 Commits • 2 Features
Jan 1, 2025January 2025 monthly summary for ERGO-Code/HiGHS. Focused on robustness, correctness, and performance improvements across presolve, MIP timing/logging, and solver core. Delivered key features and fixes with measurable business value in reliability, speed, and maintainability.
January 2025
December 2024
17 Commits • 3 Features
Dec 1, 2024December 2024 monthly summary for ERGO-Code/HiGHS: Delivered major features to the solver’s cut-generation and presolve paths, plus targeted code-quality improvements. Key outcomes include robust cut-generation refactor, enhanced presolve/integral-detection, and broad solver code cleanups that reduce risk and simplify future work.
December 2024
17 Commits • 3 Features
Dec 1, 2024December 2024 monthly summary for ERGO-Code/HiGHS: Delivered major features to the solver’s cut-generation and presolve paths, plus targeted code-quality improvements. Key outcomes include robust cut-generation refactor, enhanced presolve/integral-detection, and broad solver code cleanups that reduce risk and simplify future work.
November 2024
18 Commits • 2 Features
Nov 1, 2024November 2024 focused on strengthening HiGHS solve reliability and constructive enhancements in presolve and LP transformation. Deliverables improved solution quality, reduced edge-case failures, and expanded the solver’s cut-generation capabilities, directly supporting more robust gives-to-solve performance on enterprise workloads.
18 Commits • 2 Features
Nov 1, 2024November 2024 focused on strengthening HiGHS solve reliability and constructive enhancements in presolve and LP transformation. Deliverables improved solution quality, reduced edge-case failures, and expanded the solver’s cut-generation capabilities, directly supporting more robust gives-to-solve performance on enterprise workloads.
November 2024
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Quality Metrics
Correctness90.0%
Maintainability90.0%
Architecture85.0%
Performance83.0%
AI Usage20.2%
Skills & Technologies
Programming Languages
CC++LPMPStext
Technical Skills
Academic ResearchAlgorithm DesignAlgorithm DevelopmentAlgorithm EnhancementAlgorithm ExplanationAlgorithm ImplementationAlgorithm ImprovementAlgorithm OptimizationAlgorithm RefactoringAlgorithm RefinementAssertionBug FixBug FixingBuild SystemsC programming
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