Abstract
Consider an integral equation \(\lambda \; u - T u = f\), where T is an integral operator, defined on C[0, 1], with a kernel having an algebraic or a logarithmic singularity. Let \(\pi _m\) denote an interpolatory projection onto a space of piecewise polynomials of degree \(\le r - 1\) with respect to a graded partition of [0, 1] consisting of m subintervals. In the product integration method, an approximate solution is obtained by solving \(\lambda \; u_m - T \pi _m u_m = f.\) As in order to achieve a desired accuracy, one may have to choose m large, we find approximations of \(u_m\) using a discrete modified projection method and its iterative version. We define a two-grid iteration scheme based on this method and show that it needs less number of iterates than the two-grid iteration scheme associated with the discrete collocation method. Numerical results are given which validate the theoretical results.
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The third author was partially supported by CMUP, which is financed by national funds through FCT - Fundação para a Ciência e Tecnologia, I.P., under the project with reference UIDB/00144/2020.
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Grammont, L., Kulkarni, R.P. & Vasconcelos, P.B. Fast and accurate solvers for weakly singular integral equations. Numer Algor 92, 2045–2070 (2023). https://doi.org/10.1007/s11075-022-01376-x
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DOI: https://doi.org/10.1007/s11075-022-01376-x
Keywords
- Algebraic singularity
- Logarithmic singularity
- Collocation method
- Interpolatory projection
- Graded mesh
- Piecewise polynomial approximation
- Product integration
- Weakly singular integral operator