Ytukyg

Is there a way to have lineno show line numbers for a paragraph that uses the align environment?

In the following example, the (first) paragraph that ends with begin{align} ... end{align} does not have the desired line numbers, whereas the (second) paragraph that separates the text with a single new line contains the line numbers.

documentclass{article}



usepackage{amsmath}

usepackage[mathlines]{lineno}

usepackage{lipsum}



linenumbers

title{My Document}

author{Anonymous Anteater}



begin{document}

maketitle



Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

culpa qui officia deserunt mollit anim id est laborum.

begin{align}

x = 2

end{align}

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

culpa qui officia deserunt mollit anim id est laborum.



Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis



begin{align}

x = 2

end{align}



end{document}

The lineno package is not compatible with the amsmath environments, but the two can be made to work together.

Here is (a slightly updated version of) the patch for the amsmath environments that I wrote for it as an answer to this question.

documentclass{article}



usepackage{amsmath}

usepackage[mathlines]{lineno}



usepackage{etoolbox} %% <- for pretocmd, apptocmd and patchcmd



%% Patch 'normal' math environment: (currently unused, but good to have)

% newcommand*linenomathpatch[1]{%

%   expandafterpretocmdcsname #1endcsname {linenomath}{}{}%

%   expandafterpretocmdcsname #1*endcsname{linenomath}{}{}%

%   expandafterapptocmdcsname end#1endcsname {endlinenomath}{}{}%

%   expandafterapptocmdcsname end#1*endcsname{endlinenomath}{}{}%

% }

%% Patch AMS math environment:

newcommand*linenomathpatchAMS[1]{%

  expandafterpretocmdcsname #1endcsname {linenomathAMS}{}{}%

  expandafterpretocmdcsname #1*endcsname{linenomathAMS}{}{}%

  expandafterapptocmdcsname end#1endcsname {endlinenomath}{}{}%

  expandafterapptocmdcsname end#1*endcsname{endlinenomath}{}{}%

}



%% Definition of linenomathAMS depends on whether the mathlines option is provided

expandafterifxlinenomathlinenomathWithnumbers

  letlinenomathAMSlinenomathWithnumbers

  %% The following line gets rid of an extra line numbers at the bottom:

  patchcmdlinenomathAMS{advancepostdisplaypenaltylinenopenalty}{}{}{}

else

  letlinenomathAMSlinenomathNonumbers

fi



% linenomathpatch{equation} %% <- unnecessary, equation is already patched

linenomathpatchAMS{gather}

linenomathpatchAMS{multline}

linenomathpatchAMS{align}

linenomathpatchAMS{alignat}

linenomathpatchAMS{flalign}



linenumbers

title{My Document}

author{Anonymous Anteater}



begin{document}

maketitle



Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

culpa qui officia deserunt mollit anim id est laborum.

begin{align*}

    nabla cdot E &= frac{rho}{varepsilon_0}

    &

    nabla times E &= - frac{partial}{partial t}

    \

    nabla cdot B &= 0

    &

    nabla times B &= mu_0 J + mu_0 varepsilon_0 frac{partial E}{partial t}

end{align*}

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

culpa qui officia deserunt mollit anim id est laborum.



Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis

[

    i hbar frac{d}{dt} lvert Psi(t) rangle = hat H lvert Psi(t) rangle.

]



end{document}

Some details

The following excerpts are from the lineno documentation:

lineno.sty does not work well with display math. The parts of a
paragraph preceeding a display math will not get line numbers. The
reason is that the paragraph is not finished, but the part above the
display is broken into lines anyway.

[…]

lineno.sty defines a {linenomath} environment, which can be wrapped around a display math to make the line numbering work. This will work with any kind of display math, even if you use explicit $$ pairs. There is a *-form {linenomath*}which also numbers the lines of the display itself, as good as it can.

To use the align environment together with the lineno package, you thus need to wrap the environment between begin{linenomath} and end{linenomath}, like this:

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

culpa qui officia deserunt mollit anim id est laborum.

begin{linenomath}begin{align}

x = 2

end{align}end{linenomath}

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor

culpa qui officia deserunt mollit anim id est laborum.

Because this is a hassle, the standard math environments are automatically patched to include linenomath and endlinenomath.
The environments that are patched are displaymath, equation, equation*, eqnarray and eqnarray*, as well as the macros [ and ].
If the mathlines option is provided to lineno, then the lines within these equations are also numbered.

The amsmath environments are not patched because (from the documentation):

This will probably not work with AMSmath.

It actually works fine, apart from the fact that each of the amsmath environments receives an additional line number at the end.
The macro linenomathpatchAMS, which I define above, performs a modified version of this patch that gets rid of this extra line number. (For more details, see here.)

The only environment that still misbehaves is multline, which has an extra equation number at the top.

One way is to replace the align by

[

  begin{aligned}

    x = 2

  end{aligned}

]

or by

begin{equation}

 begin{aligned}

   x = 2

 end{aligned}

end{equation}

if you want numbered version.