How can I fix the small gaps in \hhline and make it (and double vertical lines) intransparent to particular vertical (horizontal) lines?

Question

Take a look at this table:

\documentclass[12pt,a4paper]{report}
\usepackage[ngerman]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[activate={true,nocompatibility},final,tracking=false,kerning=true,spacing=true,factor=1100,stretch=10,shrink=10]{microtype}
\DisableLigatures[f]{encoding = T1}
\usepackage{color}
\usepackage{etoolbox}
\microtypecontext{spacing=nonfrench}
\usepackage{geometry}
\usepackage{multirow}
\usepackage{hhline}
\usepackage{float}
\geometry{
    left=2cm,
    right=2cm,
    top=2cm,
    bottom=2cm,
    bindingoffset=0mm
}
\begin{document}
    \begin{table}[H]
        \centering
        \begin{tabular}{c|c||cc|cc|cc}
            & $\boldsymbol{(1 - \tau_0) i}$ & \multicolumn{2}{c|}{\multirow{2}{*}{$\boldsymbol{\alpha = 0{,}01}$}} & \multicolumn{2}{c|}{\multirow{2}{*}{$\boldsymbol{\alpha = 0{,}02}$}} & \multicolumn{2}{c}{\multirow{2}{*}{$\boldsymbol{\alpha = 0{,}03}$}} \\
            $\boldsymbol{i}$ & $\boldsymbol{=}$ & \multicolumn{2}{c|}{} & \multicolumn{2}{c|}{} & \multicolumn{2}{c}{}\\
            & $\boldsymbol{0{,}25}$ & $\boldsymbol{n = 0{,}04}$ & $\boldsymbol{n = 0{,}05}$ & $\boldsymbol{n = 0{,}04}$ & $\boldsymbol{n = 0{,}05}$ & $\boldsymbol{n = 0{,}04}$ & $\boldsymbol{n = 0{,}05}$\\ \hhline{=|=#==|==|==}
            $0{,}05$ & $0{,}0375$ & $\infty$ & $\infty$ & $\infty$ & $\infty$ & $\infty$ & $\infty$\\ \hline
            $0{,}06$ & $0{,}0450$ & $42{,}16$ & $\infty$ & $51{,}35$ & $\infty$ & $52{,}85$ & $\infty$\\ \hline
            $0{,}07$ & $0{,}0525$ & $23{,}11$ & $47{,}03$ & $32{,}30$ & $57{,}24$ & $33{,}79$ & $58{,}78$\\ \hline
            $0{,}08$ & $0{,}0600$ & $14{,}69$ & $21{,}97$ & $23{,}89$ & $32{,}19$ & $25{,}38$ & $33{,}37$
        \end{tabular}
    \end{table}
\end{document}

Using \usepackage{hhline} enables me to draw a double horizontal line which is transparent for vertical lines:

It even enables double vertical lines with the help of #:

But taking a closer look reveals that \hhline is comprised of several small lines which leave gaps inbetween:

I would like to get rid of these gaps, but I don’t know how. This is no solution for me.

Furthermore, I would like the double horizontal and vertical line to interrupt all intersecting lines. Also, I would like to deactivate # so that neither the double horizontal nor the double vertical line can interrupt each other. This would/should look like this:

 ___| |___
 ___   ___
    | |

Instead of:

 ___|_|___
 ___|_|___
    | |

score 3 · Accepted Answer · answered Feb 10 '18 at 14:57

You can use :: to get an open crossing instead of # however the lines are made by drawing a line in each cell, so they are separate lines which start and stop at the same point. Some PDF viewers may show a small gap due to rounding to pixel boundaries, some are better at avoiding that.

It would, in principle, be possible to merge adjacent - or = segments and make a single \leaders run across the span, however that would require quite a lot of changes to the package.

score 0 · Answer 2 · answered Jul 10 '21 at 17:49

For information, in the environment {NiceTabular} of nicematrix, the vertical rules are not interrupted by the double horizontal rules specified by \hline\hline. Moreover, you won't see thin white lines, whatever PDF viewer you use, at all levels of zoom.

\documentclass[12pt,a4paper]{report}
\usepackage[ngerman]{babel}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{color}
\usepackage{geometry}
\usepackage{nicematrix}
\usepackage{float}
\geometry{
    left=2cm,
    right=2cm,
    top=2cm,
    bottom=2cm,
    bindingoffset=0mm
}
\begin{document}
    \begin{table}[H]
        \centering
        \begin{NiceTabular}{c|c||cc|cc|cc}
            & $\boldsymbol{(1 - \tau_0) i}$ & \Block{2-2}{$\boldsymbol{\alpha = 0{,}01}$} && \Block{2-2}{$\boldsymbol{\alpha = 0{,}02}$} && \Block{2-2}{$\boldsymbol{\alpha = 0{,}03}$} \
            $\boldsymbol{i}$ & $\boldsymbol{=}$ \
            & $\boldsymbol{0{,}25}$ & $\boldsymbol{n = 0{,}04}$ & $\boldsymbol{n = 0{,}05}$ & $\boldsymbol{n = 0{,}04}$ & $\boldsymbol{n = 0{,}05}$ & $\boldsymbol{n = 0{,}04}$ & $\boldsymbol{n = 0{,}05}$\ 
            \hline\hline
            $0{,}05$ & $0{,}0375$ & $\infty$ & $\infty$ & $\infty$ & $\infty$ & $\infty$ & $\infty$\ \hline
            $0{,}06$ & $0{,}0450$ & $42{,}16$ & $\infty$ & $51{,}35$ & $\infty$ & $52{,}85$ & $\infty$\ \hline
            $0{,}07$ & $0{,}0525$ & $23{,}11$ & $47{,}03$ & $32{,}30$ & $57{,}24$ & $33{,}79$ & $58{,}78$\ \hline
            $0{,}08$ & $0{,}0600$ & $14{,}69$ & $21{,}97$ & $23{,}89$ & $32{,}19$ & $25{,}38$ & $33{,}37$
        \end{NiceTabular}
    \end{table}
\end{document}

You need several compilations (because nicematrix uses PGF/Tikz nodes under the hood).

How can I fix the small gaps in \hhline and make it (and double vertical lines) intransparent to particular vertical (horizontal) lines?

2 Answers2