Multi-page equations — problem

Question

I have a very long derivation, that needs to look like:

A = B \\ = C \\ = D \\

etc. The derivation spans across many lines. I'm looking for a way to typeset it so that when it reaches the end of the page it can continue naturally on the next page, without trying to fit the entire equation into a single page. I'm currently using eqnarray and it insists that all its contents sit on a single page.

Can anyone suggest another environment that supports multi-page equations?

Answer 1

With align, page breaks in multi line equations are possible. The command \allowdisplaybreaks enables it. You can fine-tune it optionally:

• \allowdisplaybreaks[1] : page breaks are allowed, but avoided if possible
• \allowdisplaybreaks[2], ..., \allowdisplaybreaks[4] : page breaks are allowed, more relaxed

You can still use \\* to forbid a page break at places where it's undesirable.

While \allowdisplaybreaks goes into the preamble, you could also allow page breaks at certain places in the body text by \displaybreak:

• \displaybreak[0] : allows a page break after the following \\, but doesn't encourage it
• \displaybreak[1], ..., \displaybreak[3] : allows a page breaks, more relaxed
• \displaybreak[4] : forces a page break after the following \\

4 is the default value for both \displaybreak and \allowdisplaybreaks.

See: 3.9 Vertical spacing and page breaks in multiline displays in the amsmath user's guide.

Answer 2

Just add the \allowdisplaybreaks command from the amsmath package to the preamble of your document. Works only with the math environments provided by this package. The manual describes the details. Take a look at the excellent »Math mode« document for more information about math typesetting.