Let $f : \mathbb{R}^n \to \mathbb{R}^m$ be an D3997: Even euclidean real function.
Let $f_{\mathsf{even}} : \mathbb{R}^n \to \mathbb{R}^m$ be the D4692: Euclidean real function even part of $f$.

Then \begin{equation} f = f_{\mathsf{even}} \end{equation}