cosine function intersects the line . Not all fixed points are attracting. For example, 0 is a fixed point of the function f(x) = 2x, but iteration of this function for any value other than zero rapidly diverges. We say that the fixed point of is repelling. An attracting fixed point is said to be a stable fixed point if it is also Lyapunov stable. A fixed point is said to be a neutrally stable fixed point if it is Lyapunov stable but not attracting. The center of a linear homogeneous differential equation of the second order is an example of a neutrally stable fixed point. Multiple attracting points can be collected in an attracting fixed set. Banach fixed-point theorem The Banach fixed-point theorem gives a sufficient condition for the existence of attracting fixed points. A contraction mapping function defined on a complete metric space has precisely one fixed point, and the fixed-point iteration is attracted towards that fixed point for any initial guess in the domain of the function. Common special cases are that (1) is defined on the real line with real values and is Lipschitz continuous with Lipschitz constant , and (2) the function f is continuously differentiable in an open neighbourhood of a fixed point xfix, and . Although there are other fixed-point theorems, this one in particular is very useful because not all fixed-points are attractive. When constructing a fixed-point iteration, it is very important to make sure it converges to the fixed point. We can usually use the Banach fixed-point theorem to show that the fixed point is attractive. Attractors Attracting fixed points are a special case of a wider mathematical concept of attractors. Fixed-point iterations are a discrete dynamical system on one variable. Bifurcation theory studies dynamical systems and classifies various behaviors such as attracting fixed points, periodic orbits, or strange attractors. An example system is the logistic map. Iterative methods In computational mathematics, an iterative method is a mathematical procedure that uses an initial value to generate a sequence of improving approximate solutions for a class of problems, in which the n-th approximation is derived from the previous ones. Convergent fixed-point iterations are mathematically rigorous formalizations of iterative methods. Iterative method examples Convergence acceleration The speed of convergence of the iteration sequence can be increased by using a convergence acceleration method such as Anderson acceleration and Aitken's delta-squared process. The application of