noun
single-valued function
A function that assigns exactly one output to each input. Used in mathematics.
一価関数では、一つの入力に対して一つの出力が定まる。
In a single-valued function, one output is determined for each input.
多価関数 is a multi-valued function, which can assign multiple outputs to a single input, in contrast to 一価関数.
Compound of 一価 (いっか, 'single-valued') and 関数 (かんすう, 'function'). The term is a direct calque from English 'single-valued function'.