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Main Authors: Linghu, Yuxuan, Liu, Zhiyuan, Deng, Qi
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.14154
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author Linghu, Yuxuan
Liu, Zhiyuan
Deng, Qi
author_facet Linghu, Yuxuan
Liu, Zhiyuan
Deng, Qi
contents Differentiating through the solution of a quadratic program (QP) is a central problem in differentiable optimization. Most existing approaches differentiate through the Karush--Kuhn--Tucker (KKT) system, but their computational cost and numerical robustness can degrade at scale. To address these limitations, we propose dXPP, a penalty-based differentiation framework that decouples QP solving from differentiation. In the solving step (forward pass), dXPP is solver-agnostic and can leverage any black-box QP solver. In the differentiation step (backward pass), we map the solution to a smooth approximate penalty problem and implicitly differentiate through it, requiring only the solution of a much smaller linear system in the primal variables. This approach bypasses the difficulties inherent in explicit KKT differentiation and significantly improves computational efficiency and robustness. We evaluate dXPP on various tasks, including randomly generated QPs, large-scale sparse projection problems, and a real-world multi-period portfolio optimization task. Empirical results demonstrate that dXPP is competitive with KKT-based differentiation methods and achieves substantial speedups on large-scale problems. Our implementation is open source and available at https://github.com/mmmmmmlinghu/dXPP.
format Preprint
id arxiv_https___arxiv_org_abs_2602_14154
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Penalty Approach for Differentiation Through Black-Box Quadratic Programming Solvers
Linghu, Yuxuan
Liu, Zhiyuan
Deng, Qi
Machine Learning
Optimization and Control
Differentiating through the solution of a quadratic program (QP) is a central problem in differentiable optimization. Most existing approaches differentiate through the Karush--Kuhn--Tucker (KKT) system, but their computational cost and numerical robustness can degrade at scale. To address these limitations, we propose dXPP, a penalty-based differentiation framework that decouples QP solving from differentiation. In the solving step (forward pass), dXPP is solver-agnostic and can leverage any black-box QP solver. In the differentiation step (backward pass), we map the solution to a smooth approximate penalty problem and implicitly differentiate through it, requiring only the solution of a much smaller linear system in the primal variables. This approach bypasses the difficulties inherent in explicit KKT differentiation and significantly improves computational efficiency and robustness. We evaluate dXPP on various tasks, including randomly generated QPs, large-scale sparse projection problems, and a real-world multi-period portfolio optimization task. Empirical results demonstrate that dXPP is competitive with KKT-based differentiation methods and achieves substantial speedups on large-scale problems. Our implementation is open source and available at https://github.com/mmmmmmlinghu/dXPP.
title A Penalty Approach for Differentiation Through Black-Box Quadratic Programming Solvers
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2602.14154