Math, Numerics, and Software



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My name is Reid Atcheson. I am a senior performance engineer at Cruise. I have a PhD in Computational and Applied Mathematics (CAAM) from Rice University, though the department recently changed its name to Computational Applied Mathematics and Operations Research (CMOR). I periodically write here about my interests. I have interest in the following:

Writing



29 Aug 2022 A Sparse Matrix Family to Confound All Solvers
16 Jul 2022 Using Jax to Compute Block-Low-Rank Format Preconditioners on Graphics Cards
11 Jun 2022 Benchmarking Rust's ndarray crate against plain slices
16 Apr 2022 Addendum To Previous Post: A Note about Shifted-Skew Solvers
12 Apr 2022 Interesting Sparse Nonsymmetric+Definite Linear Solver
12 Jan 2022 Rust Underperforms g++ On Graviton2 for Floating-Point Intensive Code
08 Jan 2022 Repeating Rust Floating-Point Benchmark on AWS Graviton2 (AARCH64) Instance
23 Nov 2021 Lessons Learned Implementing Sparse QR Factorization in Rust
23 Aug 2021 Model Reduction for a Parameterized Linear System
08 Mar 2021 Significant Performance Variation in Sparse LU Factorizations
26 Feb 2021 More Fun with Rust Iterators: Matrix-Matrix Multiply
07 Feb 2021 Visualizing Nested Dissection
07 Feb 2021 Nested Dissection for Sparse QR Factorization (video)
03 Feb 2021 Compressing the Sparse QR Factorization with Nested Dissection and Block Low-Rank Approximation
27 Jan 2021 An Interesting Inverse Inequality: Proof
24 Jan 2021 Conjecture Proven: New arXiv Manuscript Up
11 Jan 2021 Does QR Factorization Solve Linear Systems More Accurately Than Dense LU Factorization?
13 Nov 2020 Research in Progress: Nested Dissection Sparse QR Factorization
23 Oct 2020 Characterizing GMRES Convergence Part 1.4: Preconditioning Example
16 Oct 2020 Characterizing GMRES Convergence Part 1: Not Just Conditioning
21 Jul 2020 Waning Sars-Cov2 Immunity, Yet Another SIR Model
28 Apr 2020 Smoothing Covid19 Cases Data with Linear Programming
19 Oct 2019 Rust and C++ on Floating-point Intensive Code
18 May 2019 Recovering Sparsity from Noisy Data
21 Apr 2019 Fitting Noisy Data with Outliers
25 Mar 2019 Division Using only Multiply and Add
20 Mar 2019 7 Dubious Solutions to Approximate Floating-Point Equality
09 Mar 2019 Performance Results of Low-Rank Trick
03 Mar 2019 Quickly Discover Low-Rank Structure with GMRES
27 Feb 2019 Linear Algebra Secrets: Low Rank Updates
04 Aug 2018 I am a Below Average Quake Champions Player
26 May 2018 What to do when Julia's lufact runs out of memory
19 Mar 2018 Rice HPC Oil&Gas Conference 2018
15 Jan 2018 Estimating Errors in Summing Arrays of Floating Point Numbers
10 Jan 2018 Breaking Bayesian Inference
02 Jan 2018 Excluded Middle and the Stock Market
28 Dec 2017 Intermediate Value Theorem on Rational Numbers
14 Dec 2017 Computing Square Root of Rational Numbers
14 Nov 2017 Talk at SC17
02 Apr 2017 Rice HPC Oil&Gas Conference
22 Dec 2016 Abstract Numerical Linear Algebra: Update!
19 Oct 2016 Joint Post with Julia Computing
14 Oct 2016 Abstract Numerical Linear Algebra
27 Dec 2015 Running MPI Jobs on Google Compute Instances
07 Dec 2015 The danger of variable length arrays in C99+
12 Jul 2015 An International Mathematical Olympiad Problem
23 Apr 2015 I am a doctor now
07 Dec 2014 Infinitude of Primes Revisited
29 Aug 2014 JuliaCon Presentation
06 Jul 2014 Reciprocal Sum of Primes Diverges
04 Jul 2014 Infinitely many prime numbers: Euler's proof
10 Jan 2014 First website.