# why pdf file is empty? Latex generates no output, no error

one of the auto-generated latex code, for some reason, generates no output in pdf.

I made a MWE that has this latex code in it, all inside $....$, and then run pdflatex but the file is empty.

Please do not complain about the latex code itself, or why I am trying to typeset this, I am just trying to find out why pdflatex and latex produces no output at all for this input, that is all, and if there something I need to do to make it generate output, even it is not typesetted right. (this code was generated by Maple latex command, fyi)

I put the .tex file and the log file and the pdf file in this folder

>pdflatex no_output.tex
This is pdfTeX, Version 3.14159265-2.6-1.40.15 (TeX Live 2014)
restricted \write18 enabled.
entering extended mode
(./no_output.tex
LaTeX2e <2014/05/01>
....
pfb></usr/local/texlive/2014/texmf-dist/fonts/type1/public/amsfonts/cm/cmti12.p
Output written on no_output.pdf (1 page, 111713 bytes).
Transcript written on no_output.log.


But the pdf file is empty. I looked at the log file, but do not see something obvious, but I am no expert of what it is saying there really.

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Your pdf is not empty, it contains the page number on the footer. –  Sigur Jul 26 '14 at 2:22
Ow!! With that tooooo long equation it is impossible to print it... lol No way. –  Sigur Jul 26 '14 at 2:23

The equation is way to wide. \maxdimen is 16383.99998 pt = 1073741823 sp = (230 - 1) sp≈ 5.76 m. I can fit the equation to \maxdimen only, if the font size is reduced dramatically:

\documentclass[12pt]{article}
\usepackage{fix-cm}% to provide smooth tiny font sizes
\usepackage{amsmath,mathtools}
\usepackage[
paperwidth=\maxdimen,% normal paper width is hopeless
hmargin=0pt,
]{geometry}
\begin{document}

\fontsize{2.65pt}{3pt}\selectfont
\showboxdepth=2
\tracingonline=1
\AtEndDocument{\nonstopmode\showlists}
$...$
\end{document}


TeX reports (\showlists) for the equation box:

\hbox(7.02252+6.27673)x16313.41013, shifted 35.29494, display


The width is already pretty close to \maxdimen.

Without \fontsize setting:

 \hbox(31.8003+27.96019)x-12840.86679, shifted 14612.4334, display


TeX stores the dimen values as signed integers with 32 bit. Calculations with results beyond the allowed range gives Arithmetic overflow errors. Boxes are special, they can accumulate elements with the box dimensions outside the allowed range, e.g.:

\setbox0=\hbox{\kern100000pt\kern10000pt}
\showthe\wd0
> 18000.0pt.


However, the result must fit into a signed integer with 32 bit (unit sp). Beyond the values are wrapped around, continuing in the negative range:

\setbox0=\hbox{\kern10000pt\kern10000pt\kern10000pt\kern10000pt}
\showthe\wd0
> -25536.0pt.


This happened with your long equation. Because the values are no longer correct TeX miscalculates the centering of the equation dramatically (screenshot from xpdf with "fit width"):

The wraparound has the curious effect that the very end of the equation can be seen on the left side and the start of the equation on the right side. The main part in the middle of the equation is outside the paper.

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