The thirteenth lecture in Dr Joel Feinstein's G11FPM Foundations of Pure Mathematics module covers Informal definition of function, along with associated notation and terminology, including domain, codomain, argument, value, and notation.
Definition of the graph of a function, with notation and examples.
Formal definition of function (Bourbaki approach).
These videos are also available for download on iTunes U at: itunes.apple.com/us/itunes-u/foundations-pure-mathematics/id950755120
Dr Feinstein's blog may be viewed at: explainingmaths.wordpress.com.
Dr Joel Feinstein is an Associate Professor in Pure Mathematics at the University of Nottingham.