Multivalued function

A multivalued function (multifunction) is a relation like a function.  A multifunction associates each input with at least one output.  A strict function associates each input with exactly one output.  An example of a multivalued function is the square root.  Every complex number (except for 0), has two square roots.  Example:  could be 2 or -2 because  and .

 References 

Category:Functions and mappings