Identity function

Function that returns its argument unchanged

In mathematics, an identity function, also called an identity relation, identity map or identity transformation, is a function that always returns the value that was used as its argument, unchanged. That is, when f {\displaystyle f} is the identity function, the equality f ( x) = x {\displaystyle f(x)=x} is true for all values of x {\displaystyle x} to which f {\displaystyle f} can be applied.

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