What is Fixed point: Definition and 103 Discussions
In mathematics, a fixed point (sometimes shortened to fixpoint, also known as an invariant point) of a function is an element of the function's domain that is mapped to itself by the function. That is to say, c is a fixed point of the function f if f(c) = c. This means f(f(...f(c)...)) = f n(c) = c, an important terminating consideration when recursively computing f. A set of fixed points is sometimes called a fixed set.
For example, if f is defined on the real numbers by
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{\displaystyle f(x)=x^{2}-3x+4,}
then 2 is a fixed point of f, because f(2) = 2.
Not all functions have fixed points: for example, f(x) = x + 1, has no fixed points, since x is never equal to x + 1 for any real number. In graphical terms, a fixed point x means the point (x, f(x)) is on the line y = x, or in other words the graph of f has a point in common with that line.
Points that come back to the same value after a finite number of iterations of the function are called periodic points. A fixed point is a periodic point with period equal to one. In projective geometry, a fixed point of a projectivity has been called a double point.In Galois theory, the set of the fixed points of a set of field automorphisms is a field called the fixed field of the set of automorphisms.
Hi,
I need to prove that f(x) has a fixed point, given that f'(x) >= 2 for all x.
my problem is that I've reached the part in which g(x) = f(x) - x
and g'(x) = f'(x) - 1 and therefore g'(x) >= 1
but now I'm completely stuck. I knwo that I need to use the mean value theorem, but i just...
I'm trying to work out how an existence of a fixed point is linked to the constraint on the differential of that function.
For example, i need to prove f has a fixed point if f'(x)=>2.
I understand that what I have is a monotone increasing function so it is 1-1. All the fixed points are...
I have read the following :
"The usual proof of Brouwer's fixed-point theorem makes use of some machinery from simplical homology theory. First we establish that there does not exist a "retraction" of an n-cell onto its boundary, which is to say, there is no continuous mapping from an n-cell...