# [OS X TeX] RE: Beamer bug?

Lantz Susan lantzs at trine.edu
Wed Oct 8 15:27:00 EDT 2008

Chris,

I have run into this same problem, with tables---and also with
gather*-ed and align*-ed   equations---but I was *not* using
\beamertemplatetransparentcovereddynamic.

I was using

\mode<presentation>
{
\usetheme{Warsaw}
\setbeamercovered{transparent}
}

I had to display all my gather*-ed equations at the same time, instead
of line by line. When I tried to do it line by line, the first symbol on
the subsequent lines was greyed out, but the remainder of the line was
very much present. (As in your table example.)

The example below shows both the problem and my
I'm-new-to-beamer-and-fiddling-around-for-a-solution fix.

If anyone sees something I'm overlooking or have done wrong, please let
me know!

Susan Lantz

Susan A. Lantz, Ph.D.
Department of Mechanical & Aerospace Engineering
Trine University
Angola, IN 46703

-----------------------

% Filename: Beamer-ex.tex
% Typeset with LaTeX

\documentclass{beamer}
\mode<presentation>
{
\usetheme{Warsaw}
\setbeamercovered{transparent}
}

\usepackage[english]{babel}
\usepackage[latin1]{inputenc}
\usepackage{times}
\usepackage[T1]{fontenc}

\title%[Short Paper Title]
{Manufacturing Processes \& Equipment}

\subtitle
{Shaping Processes for Plastics \& Rubber} % (optional)

\author{Dr.\ Lantz}
\institute[Trine University]{Department of Mechanical Engineering\\Trine
University}

\date[Lecture 10] % (optional)
{26 September 2008}

\pgfdeclareimage[height=0.5cm]{university-logo}{trine_logo}
\logo{\pgfuseimage{university-logo}}

%\AtBeginSubsection[]
%{
%  \begin{frame}<beamer>
%    \frametitle{Outline}
%    \tableofcontents[currentsection,currentsubsection]
%  \end{frame}
%}

%\beamerdefaultoverlayspecification{<+->} %% uncovers everything in
step-wise fashion

\begin{document}

\section{Shaping Processes for Plastics}
\subsection{Extrusion}

\begin{frame}
\frametitle{Melt Flow in Extruder}
$$Q_x = Q_d - Q_b$$
where $Q_d$ is the \textit{drag flow} and $Q_b$ is the \textit{back
pressure flow}.
\begin{gather*}
Q_d = 0.5\pi^2 D^2Nd_c\sin A\cos A\\
Q_b = \frac{p\pi Dd_c^3\sin^2 A}{12\eta L}
\end{gather*}
where $D$ is the diameter of the extruder barrel, $L$ is the length of
the extruder barrel, $p$ is the pitch of the screw, $d_c$ is the channel
depth, $N$ is the rotation of the screw in \textbf{\sl rev/sec}, $A$ is
the helix angle of the screw, and $\eta$ is the viscosity of the polymer
melt.
\end{frame}

\begin{frame}
\frametitle{Extrusion Example}
Example (\#13.2P) An extruder has a diameter of 5.0\,in and a
length-to-diameter ratio of 26. The barrel heats the polypropylene melt
to $450^\circ$F, which provides a melt viscosity of 0.0025\,lb-s/in$^2$.
The pitch of the screw is 4.2\,in, and the channel depth is 0.15\,in. In
operation the screw rotates at 50\,rev/min, and a head pressure of
450\,lb/in$^2$ is generated. What is the volume flow rate of
polypropylene from the die at the end of the barrel?
\end{frame}

\begin{frame}
\frametitle{Extrusion Example (cont'd)}
%% Can't display the lines within align* (or gather*) one by one; only
the first symbol on subsequent lines is greyed-out.
\begin{align*}
Q_x &= Q_d - Q_b\\
\pause
Q_d &= 0.5\pi^2 D^2Nd_c\sin A\cos A\\
\pause
Q_b &= \frac{p\pi Dd_c^3\sin^2 A}{12\eta L}\\
\pause
A &= \tan\left(\frac{p}{\pi D}\right)^{-1}
\end{align*}
\end{frame}

\begin{frame}
\frametitle{Extrusion Example (cont'd)}
$$A = \tan\left(\frac{p}{\pi D}\right)^{-1} = \tan^{-1}\left(\frac{4.2}{5\pi}\right) = 15^\circ$$
\pause
\begin{align*}
Q_d &= 0.5\pi^2 D^2Nd_c\sin A\cos A\\
&= 0.5\pi^2 \left(5.0\,\text{in}\right)^2
\left(\frac{50\,\text{rev/min}}{60\,\text{sec/min}}\right)
(0.15\,\text{in})\sin 15^\circ\cos 15^\circ\\
Q_d &= 3.9\,\text{in$^3$/sec}\\
\end{align*}
\end{frame}

\begin{frame}
\frametitle{Extrusion Example (cont'd)}
\pause
\begin{align*}
Q_b &= \frac{p\pi Dd_c^3\sin^2 A}{12\eta L}\\
&= \frac{450\pi(5.0\,\text{in})(0.15\,\text{in})^3\sin^2
15^\circ}{12(0.0025\,\text{lb-s/in}^2)(5.0\,\text{in})(26)}\\
Q_b &= 0.41\,\text{in$^3$/sec}
\end{align*}
\pause
$$Q_x = Q_d - Q_b = (3.9 - 0.41\,\text{in^3/sec}) = 3.5\,\text{in^3/sec}$$
\end{frame}

\end{document}

------------------------------------------------------

-----Original Message-----

Date: Sat, 4 Oct 2008 21:32:41 -0400
From: Christopher Menzel <cmenzel at tamu.edu>
Subject: [OS X TeX] Beamer bug?
\beamertemplatetransparentcovereddynamic +	tabular
To: "TeX on Mac OS X Mailing List" <MacOSX-TeX at email.esm.psu.edu>
Message-ID: <5011AA5F-CE76-4D1D-8A89-ACBFCDF491F5 at tamu.edu>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes

I've found what seems to be a minor Beamer bug.  The display option
\beamertemplatetransparentcovereddynamic (and related options)
together with \pause commands nicely displays increasingly faint
renditions of upcoming bullet points of a slide, as seen here:
http://cmenzel.org/Beamer.png
.  One should be able to get the same effect out of \pause for the
successive rows of a table (generated by a tabular environment).
However, this does not appear to work.  Here's a pic from a
presentation I prepared this week that illustrates the problem:
http://cmenzel.org/BeamerBug.png
.  I have a \pause command inserted after the code for each row of
the table and, in this slide, the presentation is \pause'd due to the
occurrence of the command following the first row.  As you can see,
all of the first row is visible but only the first columns of the next
rows are visible and increasingly faint.  The second columns of those
rows should be similarly faint.  But instead the second column of
*every* row in the table is fully visible.

This appears to be a bug; if I don't use the \beamertemplate... option
the pause commands work as expected.  I could find no reference to
this issue on the web.  Any information appreciated.

Thanks.

Chris Menzel