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A sigmoid function is any mathematical function whose graph has a characteristic S-shaped or sigmoid curve . A common example of a sigmoid function is the logistic function shown in the first figure and defined by the formula: [ 1] Other standard sigmoid functions are given in the Examples section. In some fields, most notably in the context of ...
In mathematics, the domain of a function is the set of inputs accepted by the function. It is sometimes denoted by or , where f is the function. In layman's terms, the domain of a function can generally be thought of as "what x can be". [ 1] More precisely, given a function , the domain of f is X. In modern mathematical language, the domain is ...
e. In mathematics, a function from a set X to a set Y assigns to each element of X exactly one element of Y. [ 1] The set X is called the domain of the function [ 2] and the set Y is called the codomain of the function. [ 3] Functions were originally the idealization of how a varying quantity depends on another quantity.
Identity function. In mathematics, an identity function, also called an identity relation, identity map or identity transformation, is a function that always returns the value that was used as its argument, unchanged. That is, when f is the identity function, the equality f(x) = x is true for all values of x to which f can be applied.
In mathematics, an injective function (also known as injection, or one-to-one function[ 1] ) is a function f that maps distinct elements of its domain to distinct elements; that is, x1 ≠ x2 implies f(x1) ≠ f(x2). (Equivalently, f(x1) = f(x2) implies x1 = x2 in the equivalent contrapositive statement.) In other words, every element of the ...
In relational algebra, a selection (sometimes called a restriction to avoid confusion with SQL 's use of SELECT) is a unary operation written as or where: and are attribute names, is a binary operation in the set. is a value constant, is a relation. The selection selects all those tuples in for which holds between the and the attribute.
Identity function: maps any given element to itself. Constant function: has a fixed value regardless of its input. Empty function: whose domain equals the empty set. Set function: whose input is a set. Choice function called also selector or uniformizing function: assigns to each set one of its elements.
Given a function: from a set X (the domain) to a set Y (the codomain), the graph of the function is the set [4] = {(, ()):}, which is a subset of the Cartesian product.In the definition of a function in terms of set theory, it is common to identify a function with its graph, although, formally, a function is formed by the triple consisting of its domain, its codomain and its graph.