Two-dimensional graph
A two-dimensional graph is a set of points in two-dimensional space. If the points are real and if Cartesian coordinates are used, each axis depicts the potential values of a particular real variable. Often the variable on the horizontal axis is called x and the one on the vertical axis is called y, in which case the horizontal and vertical axes are sometimes called the x axis and y axis respectively. With real variables on the axes, each point in the graph depicts the values of two real variables.
Alternatively, each point in a graph may depict the value of a single complex variable. In this case, the horizontal axis is called the real axis and depicts the potential values of the real part of the complex number, while the vertical axis is called the imaginary axis and depicts the potential values of the imaginary part of the complex number.
If the relation between the two real variables is of the form where f is a function giving a single value of y associated with each admissible value of x, then the graph is called the graph of a function. The function could be a polynomial function or a transcendental function.
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