Functions

Events

Ancient Babylonians

2000 B.C.E. - 500 bc

squares, cubes and reciprocals of natural numbers

Ptolemy

100 AD - 165 AD

Computed trigonometric functions

Oresme

1350

laws of nature as laws giving a dependence of one quantity on another

Galileo

1564 - 1642

relations between variables, mapping between sets, one to one correspondence

Leibniz

August 1673

"...other kinds of lines which, in a given figure perform some function."

Euler

1707 - 1783

composition of a variable and constants
1755, functions of x

Lacroix

1797

one quantity depends on another

Cauchy

1821

dependence between functions

Fourier

1822

abscissa x and ordinates f(x), not necessary a common law

Lobachevsky

1838

required it to be continuous

Goursat

1923

Modern Definition

Suppes

1960

Precise definition, for a x,y,z, f(x)=y and f(x)=z, then y=z