Nonlinear Systems and Least-Squares

Seminorm-induced oblique projections for sparse nonlinear convex feasibility problems

  • Yair Censor
  • Alexander Segal
    • Categories Nonlinear Optimization, Nonlinear Systems and Least-Squares Tags , , ,

    Simultaneous subgradient projection algorithms for the convex feasibility problem use subgradient calculations and converge sometimes even in the inconsistent case. We devise an algorithm that uses seminorm-induced oblique projections onto super half-spaces of the convex sets, which is advantageous when the subgradient-Jacobian is a sparse matrix at many iteration points of the algorithm. Using generalized … Read more

    An inexact parallel splitting augmented Lagrangian method for large system of linear equations

  • Donghua Wu
  • Peng Zheng
    • Categories Complementarity and Variational Inequalities, Convex Optimization, Nonlinear Systems and Least-Squares

    Parallel iterative methods are power tool for solving large system of linear equations (LQs). The existing parallel computing research results are all most concentred to sparse system or others particular structure, and all most based on parallel implementing the classical relaxation methods such as Gauss-Seidel, SOR, and AOR methods e±ciently on multiprcessor systems. In this … Read more

    TRESNEI, a Matlab trust-region solver for systems of nonlinear equalities and inequalities

  • Benedetta Morini
  • Margherita Porcelli
    • Categories Bound-constrained Optimization, Nonlinear Optimization, Nonlinear Systems and Least-Squares

    The Matlab implementation of a trust-region Gauss-Newton method for bound-constrained nonlinear least-squares problems is presented. The solver, called TRESNEI, is adequate for zero and small-residual problems and handles the solution of nonlinear systems of equalities and inequalities. The structure and the usage of the solver are described and an extensive numerical comparison with functions from … Read more

    A Derivative-Free Algorithm for the Least-square minimization

  • Andrew R. Conn
  • Katya Scheinberg
  • Hongchao Zhang
    • Categories Nonlinear Optimization, Nonlinear Systems and Least-Squares Tags , , , , , ,

    We develop a framework for a class of derivative-free algorithms for the least-squares minimization problem. These algorithms are based on polynomial interpolation models and are designed to take advantages of the problem structure. Under suitable conditions, we establish the global convergence and local quadratic convergence properties of these algorithms. Promising numerical results indicate the algorithm … Read more

    On a class of limited memory preconditioners for large scale linear systems with multiple right-hand sides

  • Serge Gratton
  • Annick Sartenaer
  • Jean Tshimanga Ilunga
    • Categories Nonlinear Optimization, Nonlinear Systems and Least-Squares Tags , , ,

    This work is concerned with the development and study of a class of limited memory preconditioners for the solution of sequences of linear systems. To this aim, we consider linear systems with the same symmetric positive definite matrix and multiple right-hand sides available in sequence. We first propose a general class of preconditioners, called Limited … Read more

    Nonlinear Stepsize Control, Trust Regions and Regularizations for Unconstrained Optimization

  • Philippe L. Toint
    • Categories Bound-constrained Optimization, Nonlinear Systems and Least-Squares, Unconstrained Optimization Tags , ,

    A general class of algorithms for unconstrained optimization is introduced, which subsumes the classical trust-region algorithm and two of its newer variants, as well as the cubic and quadratic regularization methods. A unified theory of global convergence to first-order critical points is then described for this class. An extension to projection-based trust-region algorithms for nonlinear … Read more

    Adjoint Broyden a la GMRES

  • Andreas Griewank
  • Sebastian Schlenkrich
  • Andrea Walther
    • Categories Nonlinear Systems and Least-Squares Tags , , , , , ,

    It is shown that a compact storage implementation of a quasi-Newton method based on the adjoint Broyden update reduces in the affine case exactly to the well established GMRES procedure. Generally, storage and linear algebra effort per step are small multiples of n k, where n is the number of variables and k the number … Read more

    Nonlinear programming without a penalty function or a filter

  • Nicholas I. M. Gould
  • Philippe L. Toint
    • Categories Constrained Nonlinear Optimization, Nonlinear Systems and Least-Squares, Systems governed by Differential Equations Optimization Tags , , ,

    A new method is introduced for solving equality constrained nonlinear optimization problems. This method does not use a penalty function, nor a barrier or a filter, and yet can be proved to be globally convergent to first-order stationary points. It uses different trust-regions to cope with the nonlinearities of the objective function and the constraints, … Read more

    An Accelerated Newton Method for Equations with Semismooth Jacobians and Nonlinear Complementarity Problems: Extended Version

  • Christina Oberlin
  • Stephen Wright
    • Categories Complementarity and Variational Inequalities, Nonlinear Systems and Least-Squares Tags , ,

    We discuss local convergence of Newton’s method to a singular solution $x^*$ of the nonlinear equations $F(x) = 0$, for $F:\R^n \rightarrow \R^n$. It is shown that an existing proof of Griewank, concerning linear convergence to a singular solution $x^*$ from a starlike domain around $x^*$ for $F$ twice Lipschitz continuously differentiable and $x^*$ satisfying … Read more