Domain of a function
In mathematics, the domain of a function is the set of inputs accepted by the function. It is sometimes denoted by or , where is the function. In layman's terms, the domain of a function can generally be thought of as "what x can be". More precisely, given a function , the domain of is . In modern mathematical language, the domain is part of the definition of a function rather than a property of it. In the special case that and are both sets of real numbers, the function can be graphed in the Cartesian coordinate system. In this case, the domain is represented on the -axis of the graph, as the projection of the graph of the function onto the -axis. For a function , the set is called the codomain, and the set of values attained by the function (which is a subset of ) is called its range or image. Any function can be restricted to a subset of its domain. The restriction of to , where , is written as . Natural domain If a real function is given by a formula, it may be not defined for some values of the variable. In this