Evaluation of Bfloat16, Posit, and Takum Arithmetics in Sparse Linear Solvers

Fuente: arXiv
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Main Authors: Hunhold, Laslo, Quinlan, James
Format: Preprint
Published: 2024
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_version_ 1866918218056073216
author Hunhold, Laslo
Quinlan, James
author_facet Hunhold, Laslo
Quinlan, James
contents Solving sparse linear systems lies at the core of numerous computational applications. Consequently, understanding the performance of recently proposed alternatives to the established IEEE 754 floating-point numbers, such as bfloat16 and the tapered-precision posit and takum machine number formats, is of significant interest. This paper examines these formats in the context of widely used solvers, namely LU, QR, and GMRES, with incomplete LU preconditioning and mixed precision iterative refinement (MPIR). This contrasts with the prevailing emphasis on designing specialized algorithms tailored to new arithmetic formats. This paper presents an extensive and unprecedented evaluation based on the SuiteSparse Matrix Collection -- a dataset of real-world matrices with diverse sizes and condition numbers. A key contribution is the faithful reproduction of SuiteSparse's UMFPACK multifrontal LU factorization and SPQR multifrontal QR factorization for machine number formats beyond single and double-precision IEEE 754. Tapered-precision posit and takum formats show better accuracy in direct solvers and reduced iteration counts in indirect solvers. Takum arithmetic, in particular, exhibits exceptional stability, even at low precision.
format Preprint
id arxiv_https___arxiv_org_abs_2412_20268
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Evaluation of Bfloat16, Posit, and Takum Arithmetics in Sparse Linear Solvers
Hunhold, Laslo
Quinlan, James
Numerical Analysis
B.2; G.1.3; G.1.10
Solving sparse linear systems lies at the core of numerous computational applications. Consequently, understanding the performance of recently proposed alternatives to the established IEEE 754 floating-point numbers, such as bfloat16 and the tapered-precision posit and takum machine number formats, is of significant interest. This paper examines these formats in the context of widely used solvers, namely LU, QR, and GMRES, with incomplete LU preconditioning and mixed precision iterative refinement (MPIR). This contrasts with the prevailing emphasis on designing specialized algorithms tailored to new arithmetic formats. This paper presents an extensive and unprecedented evaluation based on the SuiteSparse Matrix Collection -- a dataset of real-world matrices with diverse sizes and condition numbers. A key contribution is the faithful reproduction of SuiteSparse's UMFPACK multifrontal LU factorization and SPQR multifrontal QR factorization for machine number formats beyond single and double-precision IEEE 754. Tapered-precision posit and takum formats show better accuracy in direct solvers and reduced iteration counts in indirect solvers. Takum arithmetic, in particular, exhibits exceptional stability, even at low precision.
title Evaluation of Bfloat16, Posit, and Takum Arithmetics in Sparse Linear Solvers
topic Numerical Analysis
B.2; G.1.3; G.1.10
url https://arxiv.org/abs/2412.20268