# Knurled or broken brackets and braces

Why are my brackets with gaps and sometimes even knurled shape?

How can I solve this issue without having to draw the forms with another tool (Broken matrix - gaps in brackets (solved with Tikz))

Three examples of the problem are show on the figure below:

A MWE is below. When I change lscape with pdflscape the problem disapear. I use Adobe Reader XI on Windows 7 to see the pdf. On the viewer from texniccenter the problem do not appear

\documentclass{article}%
\usepackage{lscape}
\begin{document}
\begin{landscape}
First example:
\scriptsize
$$\left\{ \begin{array}{lcc} C \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ ~~~~\vdots~~ \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \end{array} \right.$$
\end{landscape}

\newpage
\begin{landscape}
Second example:
\scriptsize
$$\left[ \begin{array}[pos]{ccccccccccccc} C \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ \vdots \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \\ \\ 0 \end{array} \right ] \newline \left[ \begin{array}[pos]{c} U \\ \\ U \\ \\ U \\ \\ U \\ \\ U \\ \\ U \\ \\ \vdots \\ \\ U \\ \\ U \\ \\ U \\ \\ U \\ \\ U \\ \\ U \\ \\ \end{array} \right ] = \left[ \begin{array}[pos]{c} R \\ \\ R \\ \\ R \\ \\ R \\ \\ R \\ \\ R \\ \\ \vdots \\ \\ R \\ \\ R \\ \\ R \\ \\ R \\ \\ R \\ \\ R \\ \\ \end{array} \right ] \label{114}$$
\end{landscape}
\end{document}

• Often, the problem is with the program you are using to render the PDF. But I'll let others chime in. – Steven B. Segletes Oct 26 '15 at 18:09
• Does this problem persist in other PDF viewers? What about different zoom levels? Also, what about the printed output? – Werner Oct 26 '15 at 18:11
• It looks the same in two computer with adobe reader XI. The zoom levels are ~160% (monitor size). I had no other viewer, but I'll test if the problem persists. And I don't know if printed it holds. – Claudia Oct 26 '15 at 18:36
• I will update question with a MWE for landscape pages... – Claudia Oct 26 '15 at 18:38
• When I zoom your MWE to 1600% or higher, the problem goes away. – Steven B. Segletes Oct 26 '15 at 18:52

As has already been pointed out in the comments to your posting, the "knurled" look of the square brackets and curly braces is an artifact created by (a) the browser that's employed to display the pdf file on-screen and (b) the screen resolution settings employed by your system. For instance, the knurled look is clearly visible if I compile your code on a 22"-screen PC (Windows 7, MikTeX2.9) and view the output using Acrobat. (Importantly, the artifact does not show up if I create a hardcopy or if I zoom in to 800% or 1600% of the normal size.) In contrast, if I compile the same code on a 13"-screen MacBookPro ("Retina Display", MacOSX 10.11.2, MacTeX2015) and view the pdf file with the built-in viewer of TeXworks, no knurling is visible at all even at 100% zoom. And, if I view the same file with Acrobat, the knurling shows up even on the MacBook...

A separate matter: You may want to look into using some of the tools of the amsmath and mathtools packages to simplify and streamline the code needed to generate the equations and expressions of interest. For instance, in the code below, I use a dcases environment instead of writing \left\{ \begin{array}{lcc} ... \end{array}\right., and I employ three bmatrix environments instead of \left\{\begin{array}{lcc} ... \end{array}\right] contstructs.

\documentclass{article}
\usepackage{lscape}
\usepackage{mathtools} % loads amsmath package automatically
\begin{document}
\scriptsize

\begin{landscape}
First example:
$$\begin{dcases} C \\ 0 \\ 0 \\ 0 \\ 0 \\ \vdots\\ 0 \\ 0 \\ 0 \\ 0 \\ 0 \\ \end{dcases}$$

\bigskip

Second example:
$$\label{114} \begin{bmatrix} C \\ 0 \\ 0 \\ 0 \\ 0 \\ 0 \\ \vdots \\ 0 \\ 0 \\ 0 \\ 0 \\ 0 \\ 0 \\ \end{bmatrix} \begin{bmatrix} U \\ U \\ U \\ U \\ U \\ U \\ \vdots \\ U \\ U \\ U \\ U \\ U \\ U \\ \end{bmatrix} = \begin{bmatrix} R \\ R \\ R \\ R \\ R \\ R \\ \vdots \\ R \\ R \\ R \\ R \\ R \\ R \\ \end{bmatrix}$$
\end{landscape}

\end{document}