Fixed point Ishikawa iterations

Fixed Point Iterations

Recall that a vector norm on R is a mapping ‖·‖ : R → R satisfying the following conditions: • ‖x‖ > 0 for x 6= 0. • ‖λx‖ = |λ|‖x‖ for x ∈ R and λ ∈ R. • ‖x+ y‖ ≤ ‖x‖+ ‖y‖ for all x, y ∈ R. Since the space Rn×n of all matrices is also a vector space, it is also possible to consider norms there. In contrast to usual vectors, it is, however, also possible to multiply matrices (that is, the matric...

Ishikawa Iterations for Equilibrium and Fixed Point Problems for Nonexpansive Mappings in Hilbert Spaces

In this paper, we introduce an iterative scheme Ishikawa-type for finding a common element of the set EP (G) of the equilibrium points of a bifunction G and the set Fix(T ) of fixed points of a nonexpansive mapping T in a Hilbert space H. We prove that the method converges strongly to an element z ∈ Fix(T ) T EP (G) which is the unique solution of the variational inequality 〈(A− γf)z, x− z〉 ≥ 0...

Anderson Acceleration for Fixed-Point Iterations

This paper concerns an acceleration method for fixed-point iterations that originated in work of D. G. Anderson [Iterative procedures for nonlinear integral equations, J. Assoc. Comput. Machinery, 12 (1965), 547-560], which we accordingly call Anderson acceleration here. This method has enjoyed considerable success and wide usage in electronic structure computations, where it is known as Anders...

Fixed Point Iterations for Real Functions

Fixed Point Iterations Using Infinite Matrices

Let £ be a closed, bounded, convex subset of a Banach space X, /: E —»E. Consider the iteration scheme defined by x"« = xQ e E, x , = ñx ), x = 2" na ,x., nal, where A is a regular weighted mean n + l ' n n * = 0 nk k o er matrix. For particular spaces X and functions /we show that this iterative scheme converges to a fixed point of /. Let X be a normed linear space, E a nonempty closed bounded...