{"title":"A distribution function from population genetics statistics using Stirling numbers of the first kind: Asymptotics, inversion and numerical evaluation","authors":"S. Chen, N. Temme","doi":"10.1090/mcom/3711","DOIUrl":"https://doi.org/10.1090/mcom/3711","url":null,"abstract":"Stirling numbers of the first kind are common in number theory and combinatorics; through Ewen's sampling formula, these numbers enter into the calculation of several population genetics statistics, such as Fu's Fs. In previous papers we have considered an asymptotic estimator for a finite sum of Stirling numbers, which enables rapid and accurate calculation of Fu's Fs. These sums can also be viewed as a cumulative distribution function; this formulation leads directly to an inversion problem, where, given a value for Fu's Fs, the goal is to solve for one of the input parameters. We solve this inversion using Newton iteration for small parameters. For large parameters we need to extend the earlier obtained asymptotic results to handle the inversion problem asymptotically. Numerical experiments are given to show the efficiency of both solving the inversion problem and the expanded estimator for the statistical quantities.","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"114 2 1","pages":"871-885"},"PeriodicalIF":0.0,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79460116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Greenberg's conjecture for real quadratic fields and the cyclotomic Z2-extensions","authors":"L. Pagani","doi":"10.1090/mcom/3712","DOIUrl":"https://doi.org/10.1090/mcom/3712","url":null,"abstract":"Let $mathcal{A}_n$ be the $2$-part of the ideal class group of the $n$-th layer of the cyclotomic $mathbb{Z}_2$-extension of a real quadratic number field $F$. The cardinality of $mathcal{A}_n$ is related to the index of cyclotomic units in the full group of units. We present a method to study the latter index. As an application we show that the sequence of the $mathcal{A}_n$'s stabilizes for the real fields $F=mathbb{Q}(sqrt{f})$ for any integer $0<f<10000$. Equivalently Greenberg's conjecture holds for those fields.","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"39 1","pages":"1437-1467"},"PeriodicalIF":0.0,"publicationDate":"2021-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73093813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Improved computation of fundamental domains for arithmetic Fuchsian groups","authors":"James Rickards","doi":"10.1090/mcom/3777","DOIUrl":"https://doi.org/10.1090/mcom/3777","url":null,"abstract":". A practical algorithm to compute the fundamental domain of an arithmetic Fuchsian group was given by Voight, and implemented in Magma. It was later expanded by Page to the case of arithmetic Kleinian groups. We combine and improve on parts of both algorithms to produce a more efficient algorithm for arithmetic Fuchsian groups. This algorithm is implemented in PARI/GP, and we demonstrate the improvements by comparing running times versus the live Magma implementation.","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"11 1","pages":"2929-2954"},"PeriodicalIF":0.0,"publicationDate":"2021-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85355990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carlos Beltrán, Laurent Bétermin, P. Grabner, S. Steinerberger
{"title":"How well-conditioned can the eigenvector problem be?","authors":"Carlos Beltrán, Laurent Bétermin, P. Grabner, S. Steinerberger","doi":"10.1090/mcom/3706","DOIUrl":"https://doi.org/10.1090/mcom/3706","url":null,"abstract":"","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"78 ","pages":"1237-1245"},"PeriodicalIF":0.0,"publicationDate":"2021-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91452714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Stability and convergence analysis for the implicit-explicit method to the Cahn-Hilliard equation","authors":"Dong Li, Chaoyu Quan, T. Tang","doi":"10.1090/mcom/3704","DOIUrl":"https://doi.org/10.1090/mcom/3704","url":null,"abstract":"","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"44 1","pages":"785-809"},"PeriodicalIF":0.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74781507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The equilateral small octagon of maximal width","authors":"Christian Bingane, Charles Audet","doi":"10.1090/mcom/3733","DOIUrl":"https://doi.org/10.1090/mcom/3733","url":null,"abstract":"A small polygon is a polygon of unit diameter. The maximal width of an equilateral small polygon with $n=2^s$ vertices is not known when $s ge 3$. This paper solves the first open case and finds the optimal equilateral small octagon. Its width is approximately $3.24%$ larger than the width of the regular octagon: $cos(pi/8)$. In addition, the paper proposes a family of equilateral small $n$-gons, for $n=2^s$ with $sge 4$, whose widths are within $O(1/n^4)$ of the maximal width.","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"5 1","pages":"2027-2040"},"PeriodicalIF":0.0,"publicationDate":"2021-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74012378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Component-by-component construction of randomized rank-1 lattice rules achieving almost the optimal randomized error rate","authors":"J. Dick, T. Goda, Kosuke Suzuki","doi":"10.1090/mcom/3769","DOIUrl":"https://doi.org/10.1090/mcom/3769","url":null,"abstract":"We study a randomized quadrature algorithm to approximate the integral of periodic functions defined over the high-dimensional unit cube. Recent work by Kritzer, Kuo, Nuyens and Ullrich (2019) shows that rank-1 lattice rules with a randomly chosen number of points and good generating vector achieve almost the optimal order of the randomized error in weighted Korobov spaces, and moreover, that the error is bounded independently of the dimension if the weight parameters, $gamma_j$, satisfy the summability condition $sum_{j=1}^{infty}gamma_j^{1/alpha}<infty$, where $alpha$ is a smoothness parameter. The argument is based on the existence result that at least half of the possible generating vectors yield almost the optimal order of the worst-case error in the same function spaces. In this paper we provide a component-by-component construction algorithm of such randomized rank-1 lattice rules, without any need to check whether the constructed generating vectors satisfy a desired worst-case error bound. Similarly to the above-mentioned work, we prove that our algorithm achieves almost the optimal order of the randomized error and that the error bound is independent of the dimension if the same condition $sum_{j=1}^{infty}gamma_j^{1/alpha}<infty$ holds. We also provide analogous results for tent-transformed lattice rules for weighted half-period cosine spaces and for polynomial lattice rules in weighted Walsh spaces, respectively.","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"2005 1","pages":"2771-2801"},"PeriodicalIF":0.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88362704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Finite element approximation and preconditioning for anisothermal flow of implicitly-constituted non-Newtonian fluids","authors":"P. Farrell, P. A. Gazca-Orozco, E. Süli","doi":"10.1090/mcom/3703","DOIUrl":"https://doi.org/10.1090/mcom/3703","url":null,"abstract":"We devise 3-field and 4-field finite element approximations of a system describing the steady state of an incompressible heat-conducting fluid with implicit non-Newtonian rheology. We prove that the sequence of numerical approximations converges to a weak solution of the problem. We develop a block preconditioner based on augmented Lagrangian stabilisation for a discretisation based on the Scott-Vogelius finite element pair for the velocity and pressure. The preconditioner involves a specialised multigrid algorithm that makes use of a space-decomposition that captures the kernel of the divergence and non-standard intergrid transfer operators. The preconditioner exhibits robust convergence behaviour when applied to the Navier-Stokes and power-law systems, including temperature-dependent viscosity, heat conductivity and viscous dissipation.","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"32 1","pages":"659-697"},"PeriodicalIF":0.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88746456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A discontinuous Galerkin pressure correction scheme for the incompressible Navier-Stokes equations: stability and convergence","authors":"R. Masri, Chen Liu, B. Rivière","doi":"10.1090/mcom/3731","DOIUrl":"https://doi.org/10.1090/mcom/3731","url":null,"abstract":"The numerical simulation of the incompressible Navier-Stokes equations presents a challenging computational task primarily because of two reasons: (a) the coupling of the velocity and pressure by the incompressibility constraint and (b) the nonlinearity of the convection term [14, 18]. The development of splitting schemes aims to overcome these difficulties by decoupling the nonlinearity in the convection term from the pressure term. For an overview of such methods, we refer to the works of Glowinski [15] and of Guermond, Minev, and Shen [18]. In this paper, we will focus on pressure correction schemes. The basic idea of a non-incremental pressure correction scheme in time was first proposed by Chorin and Temam [5, 28]. This scheme was subsequently modified by several mathematicians leading to two major variations: (1) the incremental scheme where a previous value of the pressure gradient is added [16,30] and (2) the rotational scheme where the non-physical boundary condition for the pressure is corrected by using the rotational form of the Laplacian [29]. The main contribution of our work is the theoretical analysis of a discontinuous Galerkin (dG) discretization of the pressure correction approach. We derive stability and a priori error bounds on a family of regular meshes. The discrete velocities are approximated by discontinuous piecewise polynomials of degree k1 and the discrete potential and pressure by polynomials of degree k2. Stability of the solutions is obtained under the constraint k1−1 ≤ k2 ≤ k1+1 whereas the convergence of the scheme is obtained for the case k2 = k1 − 1 because of approximation properties. The proofs are technical and rely on several tools including special lift operators. The semi-discrete error analysis of pressure correction schemes has been extensively studied, see for example the work by Shen and Guermond [21, 27]. The use","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"56 1","pages":"1625-1654"},"PeriodicalIF":0.0,"publicationDate":"2021-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80458661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Kirschmer, Fabien Narbonne, C. Ritzenthaler, Damien Robert
{"title":"Spanning the isogeny class of a power of an elliptic curve","authors":"M. Kirschmer, Fabien Narbonne, C. Ritzenthaler, Damien Robert","doi":"10.1090/MCOM/3672","DOIUrl":"https://doi.org/10.1090/MCOM/3672","url":null,"abstract":"Let \u0000\u0000 \u0000 E\u0000 E\u0000 \u0000\u0000 be an ordinary elliptic curve over a finite field and \u0000\u0000 \u0000 g\u0000 g\u0000 \u0000\u0000 be a positive integer. Under some technical assumptions, we give an algorithm to span the isomorphism classes of principally polarized abelian varieties in the isogeny class of \u0000\u0000 \u0000 \u0000 E\u0000 g\u0000 \u0000 E^g\u0000 \u0000\u0000. The varieties are first described as hermitian lattices over (not necessarily maximal) quadratic orders and then geometrically in terms of their algebraic theta null point. We also show how to algebraically compute Siegel modular forms of even weight given as polynomials in the theta constants by a careful choice of an affine lift of the theta null point. We then use these results to give an algebraic computation of Serre’s obstruction for principally polarized abelian threefolds isogenous to \u0000\u0000 \u0000 \u0000 E\u0000 3\u0000 \u0000 E^3\u0000 \u0000\u0000 and of the Igusa modular form in dimension \u0000\u0000 \u0000 4\u0000 4\u0000 \u0000\u0000. We illustrate our algorithms with examples of curves with many rational points over finite fields.","PeriodicalId":18301,"journal":{"name":"Math. Comput. Model.","volume":"42 1","pages":"401-449"},"PeriodicalIF":0.0,"publicationDate":"2021-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79735849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}