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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Parallel homotopy curve tracking on a hypercube

Chakraborty, Amal 16 September 2005 (has links)
Probability-one homotopy methods are a class of methods for solving non-linear systems of equations that are globally convergent with probability one from an arbitrary starting point. The essence of these algorithms is the construction of an appropriate homotopy map and subsequent tracking of some smooth curve in the zero set of the homotopy map. Tracking a homotopy zero curve requires calculating the unit tangent vector at different points along the zero curve. Because of the way a homotopy map is constructed, the unit tangent vector at each point in the zero curve of a homotopy map ρ<sub>α</sub>(λ,x) is in the one-dimensional kernel of the full rank n x (n + 1) Jacobian matrix Dρ<sub>α</sub>(λ,x). Hence, tracking a zero curve of a homotopy map involves evaluating the Jacobian matrix and finding the one-dimensional kernel of the n x (n + 1) Jacobian matrix with rank n. Since accuracy is important, an orthogonal factorization of the Jacobian matrix is computed. The QR and LQ factorizations are considered here. Computational results are presented showing the performance of several different parallel orthogonal factorization/triangular system solving algorithms on a hypercube, in the context of parallel homotopy algorithms for problems with small, dense Jacobian matrices. This study also examines the effect of different component complexity distributions and the size of the Jacobian matrix on the different assignments of components to the processors, and determines in what context one assignment would perform better than others. / Ph. D.

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