Function Mapping
A function maps a particular input value[math]x[/math] to a particular output [math]y[/math]. [br]The function can be seen as a black box which crunches numbers, but the relationship between numbers is fixed.
Function plotted on a graph
Normally functions in the syllabus are assumed to be continuous and the domain include all real numbers of [math]x[/math], unless otherwise specified or the function has natural domain restriction.