The Cartesian equation
With the Cartesian equation of a curve, we mean the description of a curve using a real function f of one variable x. The curve is obtained as the graph of the function. This is the set of points (x, f(x)) for which x is part of the domain of f. This is illustrated below:
Below, one finds for example the graph of f(x) = 2*cos(x)*sin(16*x):
