# Who was the first known mathematician to graph an equation?

A friend of mine pointed out that there were no graphs in Adam Smith's The Wealth of Nations, which was published in 1776. This surprised me because René Descartes (1596-1650) is well known as being the inventor of the coordinate plane, but I understand now he never actually graphed an equation.

Who was the first known mathematician to graph an equation? And if it differs, who was the first to “popularize” them?