I encountered a strange mistake in Kleppner and Kolenkow textbook “An Introduction to Mechanics” (2nd Edition, Kindle version).
This occurred in a “Note 1.1. Approximation Methods” in chapter 1.
An example uses a change of the period of a pendulum due to a little change to its length. They start with the equation ##T=2*pi*\sqrt{g/L}##, which is an upside-down form of the correct equation. It is not a typo, because the entire following analysis is based on the incorrect version. It follows they have obtained an increment of the period T (due to positive extension of the pendulum length), negative instead of positive.
I don't want be regarded a nitpicker, but I consider it an overlooked confusing bug. Or have I missed something?