 Since the 17th century many mathematicians have contributed to the theory of differentiation.In the 19th century, calculus was put on a much more rigorous footing by mathematicians such as Augustin Louis Cauchy (1789–1857), Bernhard Riemann (1826–1866), and Karl Weierstrass (1815–1897).It was also during this period that the differentiation was generalized to Euclidean space and the complex plane.