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 Creator(s):
 Jonathan Hauenstein, Margaret Regan
 Description:
Polynomials which arise via elimination can be difficult to compute explicitly. By using a pseudowitness set, we develop an algorithm to explicitly compute the restriction of a polynomial to a given line. The resulting polynomial can then be used to evaluate the original polynomial and directional derivatives along the line at any point on the given line. Several examples are used to demonstrate this new algorithm including examples of computing the critical points of the discriminant locu…
 Date Created:
 20200327
 Record Visibility:
 Public

 Creator(s):
 Jonathan Hauenstein, Martin Helmer
 Description:
Alt’s problem, formulated in 1923, is to count the number of fourbar linkages whose coupler curve interpolates nine general points in the plane. This problem can be phrased as counting the number of solutions to a system of polynomial equations which was first solved numerically using homotopy continuation by Wampler, Morgan, and Sommese in 1992. Since there is still not a proof that all solutions were obtained, we consider upper bounds for Alt’s problem by counting the number of sol…
 Date Created:
 20200303
 Record Visibility:
 Public

3
Dataset
 Creator(s):
 Jonathan Hauenstein
 Description:
Many algorithms for determining properties of real algebraic or semialgebraic sets rely upon the ability to compute smooth points. Existing methods to compute smooth points on semialgebraic sets use symbolic quantifier elimination tools. In this paper, we present a simple algorithm based on computing the critical points of some wellchosen function that guarantees the computation of smooth points in each connected compact component of a real (semi)algebraic set. Our technique is intuitive …
 Date Created:
 20200118
 Record Visibility:
 Public

 Creator(s):
 Dan Bates, David Eklund, Jonathan Hauenstein, Chris Peterson
 Description:
A fundamental problem in algebraic geometry is to decompose the solution set of a given polynomial system. A numerical description of this solution set is called a numerical irreducible decomposition and currently all standard algorithms use a sequence of homotopies forming a dimensionbydimension approach. In this article, we pair a classical result to compute a smooth point on every irreducible component in every dimension using a single homotopy together with the theory of isosingular s…
 Date Created:
 20190426
 Record Visibility:
 Public

 Creator(s):
 Jonathan Hauenstein, Jose Rodriguez
 Description:
In the field of numerical algebraic geometry, positivedimensional solution sets of systems of polynomial equations are described by witness sets. In this paper, we define multiprojective witness sets which encode the multidegree information of an irreducible multiprojective variety. Our main results generalize the regeneration solving procedure, a trace test, and numerical irreducible decomposition to the multiprojective case. Examples are included to demonstrate this new approach.
 Date Created:
 20181229
 Record Visibility:
 Public

 Creator(s):
 Jonathan Hauenstein, Alan Liddell, Sanesha McPherson, Yi Zhang
 Description:
Standard interior point methods in semidefinite programming can be viewed as tracking a solution path for a homotopy defined by a system of bilinear equations. By considering this in the context of numerical algebraic geometry, we employ numerical algebraic geometric techniques such as adaptive precision path tracking, endgames, and projective space to accurately solve semidefinite programs. We develop feasibility tests for both primal and dual problems which can distinguish between the fou…
 Date Created:
 20180410
 Record Visibility:
 Public

 Creator(s):
 Jonathan Hauenstein
 Description:
A common problem when analyzing models, such as a mathematical modeling of a biological process, is to determine if the unknown parameters of the model can be determined from given inputoutput data. Identifiable models are models such that the unknown parameters can be determined to have a finite number of values given inputoutput data. The total number of such values over the complex numbers is called the identifiability degree of the model. Unidentifiable models are models such that th…
 Date Created:
 20180309
 Record Visibility:
 Public

8
Dataset
 Creator(s):
 Samantha Sherman, Jonathan Hauenstein
 Description:
Computational tools in numerical algebraic geometry can be used to numerically approximate solutions to a system of polynomial equations. If the system is wellconstrained (i.e., square), Newton’s method is locally quadratically convergent near each nonsingular solution. In such cases, Smale’s alpha theory can be used to certify that a given point is in the quadratic convergence basin of some solution. This was extended to certifiably determine the reality of the corresponding sol…
 Date Created:
 20180308
 Record Visibility:
 Public

 Creator(s):
 Margaret Regan, Jonathan Hauenstein
 Description:
A common computational problem is to compute topological information about a real surface defined by a system of polynomial equations. Our software, called polyTop, leverages numerical algebraic geometry computations from Bertini and Bertini_real with topological computations in javaPlex to compute the Euler characteristic, genus, Betti numbers, and generators of the fundamental group of a real surface. Several examples are used to demonstrate this new software.
 Date Created:
 20180302
 Record Visibility:
 Public

 Creator(s):
 Margaret Regan, Jonathan Hauenstein
 Description:
Three key aspects of applying homotopy continuation to parameterized systems of polynomial equations are investigated. First, for parameterized systems which are homogenized with solutions in projective space, we investigate options for selecting the affine patch where computations are performed. Second, for parameterized systems which are overdetermined, we investigate options for randomizing the system for improving the numerically stability of the computations. Finally, since one is typica…
 Date Created:
 20170706
 Record Visibility:
 Public

 Creator(s):
 Jonathan Hauenstein
 Description:
The Kuramoto model describes synchronization behavior among coupled oscillators and enjoys successful application in a wide variety of fields. Many of these applications seek phasecoherent solutions, i.e., equilibria of the model. Historically, research has focused on situations where the number of oscillators, n, is extremely large and can be treated as being infinite. More recently, however, applications have arisen in areas such as electrical engineering with more modest values of n. For…
 Date Created:
 20170407
 Record Visibility:
 Public

 Creator(s):
 Jonathan Hauenstein
 Description:
StewartGough platforms are mechanisms which consist of two rigid objects, a base and a platform, connected by six legs via spherical joints. For fixed leg lengths, a generic StewartGough platform is rigid with 40 assembly configurations (over the complex numbers) while exceptional StewartGough platforms have infinitely many assembly configurations and thus have selfmotion. We define a family of exceptional StewartGough platforms called Segredependent StewartGough platforms which aris…
 Date Created:
 20170117
 Record Visibility:
 Public