Famous mathematicians who merited development of Mathematical Functions

Calculus
”We build too many walls and not enough bridges.”
Isaac Newton
1642  1727 
Riemann integral, Fourier series
”The greatest strategy is doomed if it's implemented badly.”
Georg F. Bernhard Riemann
1826  1866 
Modern mathematical terminology, notation
”Now I will have less distraction”
Leonhard Euler
1707  1783 
Calculus
”He who hasn't tasted bitter things hasn't earned sweet things.”
Gottfried Wilhelm Leibniz
1646  1716