DDE-1/Dimensionality-reduction.md

@@ -277,8 +277,8 @@ giving $`\Sigma^{-1}`$ as:
 ```math
 \Sigma^{-1} =
 \begin{bmatrix} 
-1/\sqrt(\sigma_1) & 0 \\ 
-0 & 1/\sqrt(\sigma_2) 
+1/\sqrt{\sigma_1} & 0 \\ 
+0 & 1/\sqrt{\sigma_2}
 \end{bmatrix}
 ```