Corrfunc: Blazing Fast Correlation Functions on the CPU

Manodeep Sinha1

1Centre for Astrophysics & Supercomputing, Swinburne University Of Technology, Hawthorn, VIC, Australia


How galaxies are distributed in space is determined by a combination of universal cosmological parameters, gravity, and the physics of galaxy formation. Quantifying galaxy clustering requires computing pair-wise separations — an inherently quadratic process. Consequently, comparing the observed clustering of galaxies to that theoretically predicted is both useful to advance our understanding of physics and technically challenging. Here I present Corrfunc — a suite of OpenMP-parallelized clustering codes that target current CPU micro-architecture with custom Advanced Vector Extensions AVX512F, AVX) and Streaming SIMD Extensions (SSE) intrinsics. By design, Corrfunc is highly optimized and is at least a factor of few faster than all existing public galaxy clustering correlation function routines. While Corrfunc was developed primarily with astrophysical applications in mind, the basic algorithm within Corrfunc can be easily extended for applications that require looping over neighbours up to a certain maximum spatial extent. For instance, molecular dynamics simulations, game development for modeling flocking behavior, any cross-matching between multiple datasets based on spatial separation, can potentially benefit from the Corrfunc algorithms. Corrfunc is covered by a suite of tests, extensive documentation and is publicly available at


Dr. Manodeep Sinha is a computational astrophysicist based at the Centre for Astrophysics & Supercomputing at Swinburne University, Melbourne. Dr. Sinha completed his PhD in Astronomy from The Pennsylvania State University, and is currently a Senior Research Software Scientist, working with the ARC Centre of Excellence All-Sky Astrophysics in 3D (ASTRO 3D). Dr. Sinha works at the intersection of astrophysics, statistics, high-performance computing and software engineering.


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