How can I convert a formatted text cell to latex code?

Question

I have a formatted text cell, I want to export it as latex. How can I do that? Since copy as LaTeX doesn't work, I thought of pasting it into a string and exporting, but it's a no go:

 ExportString["Let M be a TM and let \!\(\*FormBox[\(A \[SubsetEqual] \
\*SuperscriptBox[\({0, 1}\), \(*\)]\),
TraditionalForm]\). We say that \!\(\*FormBox[\(M decides A\),
TraditionalForm]\) if \!\(\*FormBox[\(\[ForAll] \\\ x \[Element] \
\*SuperscriptBox[\({0, 1}\), \(*\)]\),
TraditionalForm]\), \!\(\*FormBox[\(x \[Element] A\\\  \[Implies] \\\ \
M(x) = 1\),
TraditionalForm]\), \!\(\*FormBox[\(x \[NotElement] A\\\  \[Implies] \
M(x) = 0. \),
TraditionalForm]\) We say that  \!\(\*FormBox[\(A \[SubsetEqual] \
\*SuperscriptBox[\({0, 1}\), \(*\)]\),
TraditionalForm]\) is \!\(\*
StyleBox[\"decidable\",\nFontWeight->\"Bold\"]\) if there is a TM \
that accepts it.", "TeX"]

Answer 1

When you export the whole cell and not only its content, then you should get LaTeX code which is not one big math-environment. Maybe one easy way is to create a new notebook with

nb = CreateDocument[]

then you copy your text-cell in it and if you then Export is as "LaTeX", you get the correct code. For example, if I have this

I can simply use Export (or ExportString to show it)

ExportString[nb, "LaTeX"]

and I get

%% AMS-LaTeX Created by Wolfram Mathematica 8.0 : www.wolfram.com

\documentclass{article}
\usepackage{amsmath, amssymb, graphics, setspace}

\newcommand{\mathsym}[1]{{}}
\newcommand{\unicode}[1]{{}}

\newcounter{mathematicapage}
\begin{document}

We can use Euler{'}s formula, \(e^{inx}=\cos (nx)+i\sin (nx)\) 
where \(i\) is the imaginary unit.

\end{document}

which gives a nice pdf:

Making it usable with a palette

Here is a basic approach how to pack this into a palette.

CreatePalette[DynamicModule[{},
  Button["To LaTeX", copyToClipboard[
    StringTrim@
     StringReplace[
      ExportString[NotebookRead[SelectedNotebook[]], 
       "LaTeX"], __ ~~ "begin{document}" ~~ text__ ~~ 
        "\\end{document}" ~~ ___ :> text]]],
  Initialization :> (copyToClipboard[text_] := 
           Module[{nb},
             nb = NotebookCreate[Visible -> False];
             NotebookWrite[nb, Cell[text, "Text"]];
             SelectionMove[nb, All, Notebook];
             FrontEndTokenExecute[nb, "Copy"];
             NotebookClose[nb];
           ])
  ]
 ]

Now you get a palette with a button and what you have to do is to select the text-cell with the LaTeX code and press the button. Then you have the correct form in the clipboard and can insert it.

For my above example I get

We can use Euler{'}s formula, \(e^{inx}=\cos (nx)+i\sin (nx)\) where \(i\)
is the imaginary unit.

Acknowledgements: I stole the copyToClipboard from @szabolcs image uploader!

Answer 2

Here is my primary thought. Wish it could bring some inspirations.

First suppose we already have a Text-style Cell, then use the menu Copy As -> LaTeX:

Paste the content into a pair of quotation marks and clear extra line-breaks:

str = "\\text{Let }

 ...

 \\text{, but need some text after it.}" // 
 StringReplace[#, "\n" -> ""] &

We get strings suitable for math-mode:

"\\text{Let }M\\text{ be a }\\text{TM}\\text{ and let }A\\subseteq \
\\{0,1\\}^*\\text{. We say that }M\\text{ decides }A\\text{ if \
}\\forall x\\in \\{0,1\\}^*\\text{, }x\\in A\\Rightarrow \
M(x)=1\\text{, }x\\notin A\\Rightarrow M(x)=0\\text{. We say that \
}A\\subseteq \\{0,1\\}^*\\text{ is decidable if there is a \
}\\text{TM}\\text{ that accepts it. And here is an inline complicated \
formula: }\\sum _{k=1}^n \\frac{1}{f(k)}\\int_{\\alpha }^{\\beta } \
\\sqrt{g(x)} \\, dx\\text{, but need some text after it.}"

Then we reverse the "environment":

str2 = StringReplace[str, RegularExpression["\\\\text{(.*?)}"] :> "«$1»"]

str3 = StringReplace[str2, 
   RegularExpression["»(.*?)«"] :> 
    If[StringLength["$1"] == 0, "", "\$$1\$"]] // 
  StringReplace[#, {"«" -> "", "»" -> ""}] &

Then Copy As -> Plain Text:

Past into SE editor:

Let $M$ be a TM and let $A\subseteq \{0,1\}^*$. We say that $M$ decides $A$ if $\forall x\in \{0,1\}^*$, $x\in A\Rightarrow M(x)=1$, $x\notin A\Rightarrow M(x)=0$. We say that $A\subseteq \{0,1\}^*$ is decidable if there is a TM that accepts it. And here is an inline complicated formula: $\sum _{k=1}^n \frac{1}{f(k)}\int_{\alpha }^{\beta } \sqrt{g(x)} \, dx$, but need some text after it.

Though looks working, this procedure is very primary and buggy. e.g. The $TM$s in the original Text Cell are actually in math-mode (i.e. inputted after a Ctrl+9), but they were converted to text-mode when copy as LaTeX. And when the paragraph ends with a formula, it should be take care of with special rule.