Photo by Colin M. Gould

Tim Marrinan

Postdoctoral Research Associate
COLORAMAP Group
Department of Mathematics and Operational Research

Matrix Theory and Optimization Group
Université de Mons

Education and Professional Experience

2017-2019: Postdoctoral Research Associate (Signal & System Theory Group, Universität Paderborn)
2013-2017: PhD in Mathematics (Pattern Analysis Lab, Colorado State University)
2010-2013: MS in Mathematics (Pattern Analysis Lab, Colorado State University)
2004-2008: BA in Applied Mathematics and Geology (Whitman College)


Recent News:

  1. The published version of our paper, On a minimum enclosing ball of a collection of linear subspaces, is now available online via Linear Algebra and Its Applications.
  2. SIAM Linear Algebra Conference: Next week (May 17th – 21st) is the SIAM Linear Algebra Conference, which was originally slated to be held in New Orleans. Unfortunately it will be organized virtually, but I will give a talk on Thursday about our work on practical verification of the Sufficiently Scattered Conditions for NMF identifiability.
  3. Upcoming talks: I will be giving two talks in January. On January 6th I will speak about verifying sufficient conditions for minimum volume nonnegative matrix factorization at the Joint Math Meetings, and on January 21st I will speak about minimax nonnegative matrix factorization during EUSIPCO 2020.
  4. Congratulations to Nicolas Gillis: My post-doctoral supervisor has just published his first book, Nonnegative Matrix Factorization. The book is available for purchase from SIAM, see the book page for details.
  5. Our article, “On a minimum enclosing ball of a collection of linear subspaces” was accepted for publication in Linear Algebra and Its Applications: You can find a preprint PDF on the Publications page.
  6. New article from Sarah Marrinan, MS in Marine Fisheries Review: My talented sister just published a retrospective on the Individual Fishing Quota Program in the quarterly journal of the National Oceanic and Atmospheric Administration (NOAA). You can find an open-access PDF on their site.
  7. Congratulations to Dr. Andersen Man Shun Ang: My colleague Andersen recently passed his dissertation defense. He is the first PhD student of Nicolas Gillis to earn his doctorate. You can watch a video of his public defense or view his wonderful dissertation on his personal webpage.
  8. New code package available on the Research page: The MATLAB package minimax NMF code is now available on Research page. Given a set of matrices X_i (1≤i≤n) with the same number of rows, it computes W≥0 and H_i≥0 to minimize max1≤i≤n ||X_i – WH_i||_F^2 + λ logdet(WTW) where the second term is a volume regularizer. It outperforms existing methods in estimating endmembers (columns of W) that are only present in a small percentage of the samples.
  9. New preprint available on the Publications page: “Hyperspectral unmixing with rare endmembers via minimax nonnegative matrix factorization,” with Nicolas Gillis was accepted to EUSIPCO. We will present the paper in Amsterdam this coming January.
  10. COLORAMAP Day 2020: The yearly workshop of the COLORAMAP group was held on June 29th at UMons. We shared some lovely lectures with a variety of perspectives on nonnegative matrix factorization. Check out the updated group picture on Nicolas’ website
  11. COLORAMAP Reading Group kickoff: In March, at the start of the coronavirus lockdown in Belgium, the group launched an online reading group to keep in contact with each other while working from home, and also to expand the breadth of our math reading. If anyone is interested in joining, please send me an email.

If you have any questions, please don’t hesitate to email me:
Timothy.MARRINAN@umons.ac.be