Definition:Pointwise Maximum of Mappings/Extended Real-Valued Functions

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Definition

Let $X$ be a set, and let $f, g: X \to \overline{\R}$ be extended real-valued functions.

Let $\max$ be the max operation on $\overline{\R}$ (Ordering on Extended Real Numbers is Total Ordering ensures it is in fact defined).


Then the pointwise maximum of $f$ and $g$, denoted $\max \left({f, g}\right)$, is defined by:

$\max \left({f, g}\right): X \to \overline{\R}: \max \left({f, g}\right) \, \left({x}\right) := \max \left({f \left({x}\right), g \left({x}\right)}\right)$


Pointwise maximum thence is an instance of a pointwise operation on extended real-valued functions.

Since the ordering on $\overline{\R}$ coincides on $\R$ with the standard ordering, this definition incorporates the definition for real-valued functions.


Also see