In
mathematics, an implicit function is a generalization for the concept of a
function in which the
dependent variable may not be given explicitly in terms of the
independent variable. To give a function f explicitly is to provide a prescription for calculating the output value of the function y in terms of the input value x of the functiony = f(x) By contrast, the function is implicit if the value of y is obtained from x by solving the equationR(x,y) = 0
See more at Wikipedia.org...