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New Einstein metrics on Sp ( n ) which are non-naturally reductive

Shaoxiang Zhang, Huibin Chen (2022)

Czechoslovak Mathematical Journal

We prove that there are at least two new non-naturally reductive Ad ( Sp ( l ) × Sp ( k ) × Sp ( k ) × Sp ( k ) ) invariant Einstein metrics on Sp ( l + 3 k ) ( k < l ) . It implies that every compact simple Lie group Sp ( n ) ...

New modification of Maheshwari’s method with optimal eighth order convergence for solving nonlinear equations

Somayeh Sharifi, Massimiliano Ferrara, Mehdi Salimi, Stefan Siegmund (2016)

Open Mathematics

In this paper, we present a family of three-point with eight-order convergence methods for finding the simple roots of nonlinear equations by suitable approximations and weight function based on Maheshwari’s method. Per iteration this method requires three evaluations of the function and one evaluation of its first derivative. These class of methods have the efficiency index equal to [...] 814≈1.682 8 1 4 1 . 682 . We describe the analysis of the proposed methods along with numerical experiments including comparison...

New quasi-Newton method for solving systems of nonlinear equations

Ladislav Lukšan, Jan Vlček (2017)

Applications of Mathematics

We propose a new Broyden method for solving systems of nonlinear equations, which uses the first derivatives, but is more efficient than the Newton method (measured by the computational time) for larger dense systems. The new method updates QR or LU decompositions of nonsymmetric approximations of the Jacobian matrix, so it requires O ( n 2 ) arithmetic operations per iteration in contrast with the Newton method, which requires O ( n 3 ) operations per iteration. Computational experiments confirm the high efficiency...

New sufficient convergence conditions for the secant method

Ioannis K. Argyros (2005)

Czechoslovak Mathematical Journal

We provide new sufficient conditions for the convergence of the secant method to a locally unique solution of a nonlinear equation in a Banach space. Our new idea uses “Lipschitz-type” and center-“Lipschitz-type” instead of just “Lipschitz-type” conditions on the divided difference of the operator involved. It turns out that this way our error bounds are more precise than the earlier ones and under our convergence hypotheses we can cover cases where the earlier conditions are violated.

Newton methods for solving two classes of nonsmooth equations

Yan Gao (2001)

Applications of Mathematics

The paper is devoted to two systems of nonsmooth equations. One is the system of equations of max-type functions and the other is the system of equations of smooth compositions of max-type functions. The Newton and approximate Newton methods for these two systems are proposed. The Q-superlinear convergence of the Newton methods and the Q-linear convergence of the approximate Newton methods are established. The present methods can be more easily implemented than the previous ones, since they do not...

Nonsmooth equations approach to a constrained minimax problem

Yan Gao, Xuewen Li (2005)

Applications of Mathematics

An equivalent model of nonsmooth equations for a constrained minimax problem is derived by using a KKT optimality condition. The Newton method is applied to solving this system of nonsmooth equations. To perform the Newton method, the computation of an element of the b -differential for the corresponding function is developed.

Non-uniqueness of almost unidirectional inviscid compressible flow

Pavel Šolín, Karel Segeth (2004)

Applications of Mathematics

Our aim is to find roots of the non-unique behavior of gases which can be observed in certain axisymmetric nozzle geometries under special flow regimes. For this purpose, we use several versions of the compressible Euler equations. We show that the main reason for the non-uniqueness is hidden in the energy decomposition into its internal and kinetic parts, and their complementary behavior. It turns out that, at least for inviscid compressible flows, a bifurcation can occur only at flow regimes with...

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