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我需要在共享链接中写下公式

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我需要在共享链接中写下公式

答案1

按下该问题下方的“编辑”并复制 MathJax 代码。不过，您必须用 和 替换$$。 \[这\]适用于此示例，但并不适用于您找到的每个 MathJax 源。

% arara: pdflatex

\documentclass{article}
\usepackage{mathtools}
\DeclareMathOperator{\MSE}{MSE}
\DeclareMathOperator{\NMSE}{NMSE}

\begin{document}
Many papers use the NMSE function without ever explicitly defining it. I have always assumed that 
\[\MSE(x,y)=\frac{1}{N} \sum_i (x_i-y_i)^2\]
and
\[\NMSE(x,y)=\MSE(x,y)/\MSE(x,0) = \frac{\| x-y\|_2^2}{\| x\|_2^2}\]
where $y$ is the approximation to $x$. This gives a simple relation between NMSE and relative $\ell^2$ error. An internet search however only shows strange definitions like 
\[\frac{ \sum_i (x_i-y_i)^2}{N\sum_i (x_i)^2} \quad\text{or} \quad \frac{N \sum_i (x_i-y_i)^2}{\sum_i x_i \sum_i y_i}\]

Is my interpretation not the standard definition?
\end{document}

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