Btukfyl

In the inline math mode ($...$), if the formula is too long, LaTeX will try to break it on operators, e.g.

very long text followed by a very long equation like $a+b+c+d+e+f+g+h+i+j+k+l$ etc

may be rendered as

very long text followed

by a very long equation

like a+b+c+d+e+f+g+h+i+

j+k+l etc

However, the break won't happen if they are separated by commas, e.g.

very long text followed by a very long equation like $a,b,c,d,e,f,g,h,i,j,k,l$ etc

will overflow the page like

very long text followed

by a very long equation

like a,b,c,d,e,f,g,h,i,j,k,l

etc

How to make LaTeX able to insert line breaks after a comma too?

If the expression contains many commas then consider to break it into several math expressions, separated by commas. It reads like a list of math expressions. This way TeX can break the line.

To achieve line breaks after a comma, you could insert allowbreak after the comma and before the next math symbol. If necessary, leave a blank after allowbreak.

If you would like to have a document wide solution, you could redefine the comma. One solution, following the tip here would be:

makeatletter

defold@comma{,}

catcode`,=13

def,{%

  ifmmode%

    old@commadiscretionary{}{}{}%

  else%

    old@comma%

  fi%

}

makeatother

You could take a look at the breqn package, which is aimed at solving this problem in a general sense.

Here is a solution that doesn't make the comma globally active:

documentclass{article}



newcommand{splitatcommas}[1]{%

  begingroup

  begingrouplccode`~=`, lowercase{endgroup

    edef~{mathcharthemathcode`, penalty0 noexpandhspace{0pt plus 1em}}%

  }mathcode`,="8000 #1%

  endgroup

}



begin{document}



setlength{lineskiplimit}{2pt}setlength{lineskip}{3pt} % for this particular case



$splitatcommas{

  frac{1}{2},frac{3}{5},frac{8}{13},frac{21}{34},frac{55}{89},

  frac{144}{233},frac{377}{610},frac{987}{1597},frac{2584}{4181},

  frac{6765}{10946},frac{17711}{28657},frac{46368}{75025},

  frac{121393}{196418},frac{317811}{514229},frac{832040}{1346269},

  frac{2178309}{3524578},frac{5702887}{9227465},

  frac{14930352}{24157817},frac{39088169}{63245986},frac{102334155}{165580141}

}$



end{document}

The setting of lineskiplimit and lineskip are for the particular case where fractions are needed in the argument.

A variant that allows nesting:

documentclass{article}



newcommand{splitatcommas}[1]{%

  begingroup

  ifnummathcode`,="8000

  else

    begingrouplccode`~=`, lowercase{endgroup

      edef~{mathcharthemathcode`, penalty0 noexpandhspace{0pt plus 1em}}%

    }mathcode`,="8000

  fi

  #1%

  endgroup

}



newcommand{tuple}[1]{(splitatcommas{#1})}

newcommand{set}[1]{{splitatcommas{#1}}}



begin{document}



setlength{lineskiplimit}{2pt}setlength{lineskip}{3pt} % for this particular case



$splitatcommas{

  frac{1}{2},frac{3}{5},frac{8}{13},frac{21}{34},frac{55}{89},

  frac{144}{233},frac{377}{610},frac{987}{1597},frac{2584}{4181},

  frac{6765}{10946},frac{17711}{28657},frac{46368}{75025},

  frac{121393}{196418},frac{317811}{514229},frac{832040}{1346269},

  frac{2178309}{3524578},frac{5702887}{9227465},

  frac{14930352}{24157817},frac{39088169}{63245986},frac{102334155}{165580141}

}$



$set{

  tuple{a,b,c,d},tuple{1,2,3,4,5,6},tuple{11,22,33,44,55,66,77,88},

  tuple{a,b,c,d},tuple{1,2,3,4,5,6},tuple{11,22,33,44,55,66,77,88},

  tuple{a,b,c,d},tuple{1,2,3,4,5,6},tuple{11,22,33,44,55,66,77,88},

  tuple{a,b,c,d},tuple{1,2,3,4,5,6},tuple{11,22,33,44,55,66,77,88}

}$



end{document}

If you can split the equation into several sub equation using $, and if you are using braces use left. and right. (with dot) to balance the braces.

Example:

 $X = left{right.a$, $b$, $c$, $dleft.right}$

X = { a, b, c, d }

This should allow line breaks behind the commas.