Exploiting Data Sparsity in Matrix Algorithms for Adaptive Optics and Seismic Redatuming

  • Yuxi Hong

Student thesis: Doctoral Thesis


This thesis addresses the exponential growth of experimental data and the resulting computational complexity seen in two major scientific applications, which account for significant cycles consumed on today’s supercomputers. The first application concerns computation of the adaptive optics system in next-generation ground-based telescopes, which will expand our knowledge of the universe but confronts the astronomy community with daunting real-time computation requirements. The second application deals with emerging frequency-domain redatuming methods, e.g., Marchenko redatuming, which are game-changers in exploration geophysics. They are valuable to oil and gas applications and will soon be to geothermal exploration and carbon capture storage. However, they are impractical at industrial scale due to prohibitive computational complexity and memory footprint. We tackle the aforementioned challenges by designing high-performance algebraic and stochastic algorithms, which exploit the data sparsity structure of the matrix operator. We show that popular randomized algorithms from machine learning can also solve large covariance matrix problems that capture the correlations of wavefront sensors detecting the atmospheric turbulence for ground-based telescopes. Algebraic compression based on low-rank approximations that retains the most significant portion of the spectrum of the operator provides numerical solutions at the accuracy level required by the application. In addition, selective use of lower precisions can further reduce the data volume by trading off application accuracy for memory footprint. Reducing memory footprint has ancillary implications for reduced energy expenditure and reduced execution time because moving a word is more expensive than computing with it on today’s architectures. We exploit the data sparsity of matrices representative of these two scientific applications and propose four algorithms to accelerate the corresponding computational workload. In soft real-time control of an adaptive optics system, we design a stochastic Levenberg-Marquardt method and high-performance solver for Discrete-time Algebraic Riccati Equations. We create a tile low-rank matrix-vector multiplication algorithm used in both hard real-time control of ground-based telescopes and seismic redatuming. Finally, we leverage multiple precisions to further improve the performance of seismic redatuming applications We implement our algorithms on essentially all families of currently relevant HPC architectures and customized AI accelerators and demonstrate significant performance improvement and validated numerical solutions.
Date of AwardJun 7 2023
Original languageEnglish (US)
Awarding Institution
  • Computer, Electrical and Mathematical Sciences and Engineering
SupervisorDavid Keyes (Supervisor)


  • Numerical Linear Algebra
  • SLM
  • Adaptive Optics
  • Seismic Redatuming

Cite this