A Nyström method for second-kind Volterra integral equations on the square
Abstract
In this paper, we propose a Nyström-type method for the numerical approximation of second-kind bivariate Volterra integral equations on the unit square. The method is based on bivariate Generalized Bernstein (GB) polynomials and on a cubature formula defined on equally spaced nodes, allowing the integral operator to be discretized directly without requiring any change of variables. The use of uniform grids makes the proposed approach particularly suitable for applications in which data are naturally sampled at equidistant points.
The approximation framework relies on tensor-product GB polynomials whose degrees may differ with respect to each variable. This flexibility allows different approximation orders to be prescribed according to the regularity of the target function in each variable. As a result, the computational cost can be reduced while preserving high level of accuracy. Compared with classical Bernstein operators, the proposed GB operators achieve higher approximation orders depending on the smoothness of the approximated functions.
The resulting Nyström scheme leads to a well-conditioned linear system and is proved to be stable and convergent. Error estimates are derived in Sobolev and Zygmund spaces. Several numerical experiments are presented to validate the theoretical results and to illustrate the effectiveness of the method for kernels and right-hand side functions with different smoothness properties.
Keywords
Supporting Institution
Gruppo Nazionale Calcolo Scientifico-Istituto Nazionale di Alta Matematica (GNCS-INdAM), Fondazione di Sardegna
Thanks
This research has been accomplished within “Research ITalian network on Approximation” (RITA).
The authors are members of the Gruppo Nazionale Calcolo Scientifico-Istituto Nazionale di Alta Matematica (GNCS-INdAM), the TAA-UMI Research Group, and the SIMAI Activity Group “Numerical and Analytical Approximation of Data and Functions with Applications” (ANA&A).
References
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Details
Primary Language
English
Subjects
Numerical Analysis
Journal Section
Research Article
Authors
Early Pub Date
July 28, 2026
Publication Date
-
Submission Date
May 29, 2026
Acceptance Date
July 24, 2026
Published in Issue
Year 2026 Number: Advanced Online Publication
APA
Fermo, L., Mezzanotte, D., & Occorsio, D. (2026). A Nyström method for second-kind Volterra integral equations on the square. Constructive Mathematical Analysis, Advanced Online Publication. https://doi.org/10.33205/cma.1960169
AMA
1.Fermo L, Mezzanotte D, Occorsio D. A Nyström method for second-kind Volterra integral equations on the square. CMA. 2026;(Advanced Online Publication). doi:10.33205/cma.1960169
Chicago
Fermo, Luisa, Domenico Mezzanotte, and Donatella Occorsio. 2026. “A Nyström Method for Second-Kind Volterra Integral Equations on the Square”. Constructive Mathematical Analysis, no. Advanced Online Publication. https://doi.org/10.33205/cma.1960169.
EndNote
Fermo L, Mezzanotte D, Occorsio D (July 1, 2026) A Nyström method for second-kind Volterra integral equations on the square. Constructive Mathematical Analysis Advanced Online Publication
IEEE
[1]L. Fermo, D. Mezzanotte, and D. Occorsio, “A Nyström method for second-kind Volterra integral equations on the square”, CMA, no. Advanced Online Publication, July 2026, doi: 10.33205/cma.1960169.
ISNAD
Fermo, Luisa - Mezzanotte, Domenico - Occorsio, Donatella. “A Nyström Method for Second-Kind Volterra Integral Equations on the Square”. Constructive Mathematical Analysis. Advanced Online Publication (July 1, 2026). https://doi.org/10.33205/cma.1960169.
JAMA
1.Fermo L, Mezzanotte D, Occorsio D. A Nyström method for second-kind Volterra integral equations on the square. CMA. 2026. doi:10.33205/cma.1960169.
MLA
Fermo, Luisa, et al. “A Nyström Method for Second-Kind Volterra Integral Equations on the Square”. Constructive Mathematical Analysis, no. Advanced Online Publication, July 2026, doi:10.33205/cma.1960169.
Vancouver
1.Luisa Fermo, Domenico Mezzanotte, Donatella Occorsio. A Nyström method for second-kind Volterra integral equations on the square. CMA. 2026 Jul. 1;(Advanced Online Publication). doi:10.33205/cma.1960169
