Function
A function assigns exactly one output to each allowed input. The set of allowed inputs is its domain and the set the outputs are drawn from is its codomain. The modern definition drops any requirement that there be a formula: a function is any such assignment, however it is described, including ones no formula can capture. Nothing is a function if a single input can produce two different outputs.
Why it matters
Every quantity that depends on another is a function, so this is the object most of calculus, analysis, and applied mathematics is actually about.
Also written: functions, mapping
Where it comes up
Read about Function on Wikipedia
Sources
- Function (mathematics) Wikipedia
- Mathematical analysis WikipediaShows what the branch built on functions does with them.
