Grouped Sequency-arranged Rotation: Optimizing Rotation Transformation for Quantization for Free

Fuente: arXiv
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Main Authors: Choi, Euntae, Song, Sumin, Lim, Woosang, Yoo, Sungjoo
Format: Preprint
Published: 2025
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author Choi, Euntae
Song, Sumin
Lim, Woosang
Yoo, Sungjoo
author_facet Choi, Euntae
Song, Sumin
Lim, Woosang
Yoo, Sungjoo
contents Large Language Models (LLMs) face deployment challenges due to high computational costs, and while Post-Training Quantization (PTQ) offers a solution, existing rotation-based methods struggle at very low bit-widths like 2-bit. We introduce a novel, training-free approach to construct an improved rotation matrix, addressing the limitations of current methods. The key contributions include leveraging the Walsh-Hadamard transform with sequency ordering, which clusters similar frequency components to reduce quantization error compared to standard Hadamard matrices, significantly improving performance. Furthermore, we propose a Grouped Sequency-arranged Rotation (GSR) using block-diagonal matrices with smaller Walsh blocks, effectively isolating outlier impacts and achieving performance comparable to optimization-based methods without requiring any training. Our method demonstrates robust performance on reasoning tasks and Perplexity (PPL) score on WikiText-2. Our method also enhances results even when applied over existing learned rotation techniques.
format Preprint
id arxiv_https___arxiv_org_abs_2505_03810
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Grouped Sequency-arranged Rotation: Optimizing Rotation Transformation for Quantization for Free
Choi, Euntae
Song, Sumin
Lim, Woosang
Yoo, Sungjoo
Machine Learning
Artificial Intelligence
Computation and Language
Large Language Models (LLMs) face deployment challenges due to high computational costs, and while Post-Training Quantization (PTQ) offers a solution, existing rotation-based methods struggle at very low bit-widths like 2-bit. We introduce a novel, training-free approach to construct an improved rotation matrix, addressing the limitations of current methods. The key contributions include leveraging the Walsh-Hadamard transform with sequency ordering, which clusters similar frequency components to reduce quantization error compared to standard Hadamard matrices, significantly improving performance. Furthermore, we propose a Grouped Sequency-arranged Rotation (GSR) using block-diagonal matrices with smaller Walsh blocks, effectively isolating outlier impacts and achieving performance comparable to optimization-based methods without requiring any training. Our method demonstrates robust performance on reasoning tasks and Perplexity (PPL) score on WikiText-2. Our method also enhances results even when applied over existing learned rotation techniques.
title Grouped Sequency-arranged Rotation: Optimizing Rotation Transformation for Quantization for Free
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2505.03810