deletions | additions       diff --git a/4-Dimensions.tex b/4-Dimensions.tex  index 21270d8..07779eb 100644  --- a/4-Dimensions.tex  +++ b/4-Dimensions.tex 
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\frac{\partial}{\partial y}\begin{vmatrix} t_1 & y_1 \\ t_2 & y_2 \end{vmatrix}+  \frac{\partial}{\partial z}\begin{vmatrix} t_1 & z_1 \\ t_2 & z_2 \end{vmatrix}  \end{equation}  ...  For the unary operation we take a four-vector and make it into a cubic array \begin{equation}  \begin{vmatrix}   \textbf{i} & \textbf{j} & \textbf{k} & \textbf{l} \\  \textbf{i} & \textbf{j} & \textbf{k} & \textbf{l} \\  \textbf{i} & \textbf{j} & \textbf{k} & \textbf{l} \\  t_1 & x_1 & y_1 & z_1   \end{vmatrix}  \end{equation}