deletions | additions       diff --git a/Gaussian Coordinates.tex b/Gaussian Coordinates.tex  index 211e5bd..8b4154a 100644  --- a/Gaussian Coordinates.tex  +++ b/Gaussian Coordinates.tex 
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P: (u, v) \\  P': (u + du, v + dv),  $$  where du $du$  and dv $dv$  signify very small numbers. In a similar manner we may indicate the distance (line-interval) between P and P', as measured with a little rod, by means of the very small number ds. Then according to Gauss we have