How can I set the equation counter to behave differently for a certain Chapter?

I am writing my phd thesis, and I want to have a simple equation counter for the introduction. In general, depending on Chapter/Section, the equation number looks like (1.2.2) (Chapter 1/Section 2/Equation 2).

I would like that only in the introduction equation numbers would look like (1),(2),(3),etc, and from the next chapter, to regain their general form. How can I do that?

  • What class are you using? Is the Introduction before or after \mainmatter (if you're using this command)?
    – egreg
    May 19, 2015 at 12:36
  • I use the class memoir, and I dont recall using the command \mainmatter. May 19, 2015 at 12:59

2 Answers 2


In the intro then


at the end of the intro.

  • Cool. This does exactly what I expected. :) May 19, 2015 at 13:00
  • Could you do something like \let\theoldequation\theequation\renewcommand... at the beginning and then \let\theequation\theoldequation at the end?
    – wchargin
    May 19, 2015 at 14:39
  • @WChargin you could, yes. May 19, 2015 at 14:51

Use the package chngcntr:

In your preamble:


In the Introduction section:


After the Introduction section:


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