Cocker, Edward, an arithmetician, and a schoolmaster by profession; wrote an arithmetic, published after his death, long the text-book on the subject, and a model of its kind; gave rise to the phrase “according to Cocker” (1631‒1672).
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Cockburn, Henry, Lord * Cockney