Evaluating a polynomial on a set of points is a fundamental task in computer algebra. In this work, we revisit a particular variant called trimmed multipoint evaluation: given an n-variate polynomial with bounded individual degree d and total degree D, the goal is to evaluate it on a natural class of input points. This problem arises as a key subroutine in recent algorithmic results [Dinur; SODA '21], [Dell, Haak, Kallmayer, Wennmann; SODA '25]. It is known that trimmed multipoint evaluation can be solved in near-linear time [van der Hoeven, Schost; AAECC '13] by a clever yet somewhat involved algorithm. We give a simple recursive algorithm that avoids heavy computer-algebraic machinery, and can be readily understood by researchers without specialized background.
@InProceedings{fischer_et_al:LIPIcs.ESA.2025.89, author = {Fischer, Nick and Kallmayer, Melvin and Wennmann, Leo}, title = {{A Simple Algorithm for Trimmed Multipoint Evaluation}}, booktitle = {33rd Annual European Symposium on Algorithms (ESA 2025)}, pages = {89:1--89:11}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-395-9}, ISSN = {1868-8969}, year = {2025}, volume = {351}, editor = {Benoit, Anne and Kaplan, Haim and Wild, Sebastian and Herman, Grzegorz}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2025.89}, URN = {urn:nbn:de:0030-drops-245574}, doi = {10.4230/LIPIcs.ESA.2025.89}, annote = {Keywords: Algebraic Algorithms, Multipoint Evaluation, Interpolation, LU Decomposition} }
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