# Fraction lines?

how to bold all fraction lines like in the picture below? I used

\newcommand{\thickfrac}[2]{\genfrac{}{}{3pt}{}{#1}{#2}}


but nothing happened.

Based on the answer of user David Carlisle from this question.

\documentclass{article}

\usepackage{mathtools} % also loads the amsmath package

% Command with 2 obligatory arguments (num and denom)
\newcommand{\myThickFrac}[2]{\genfrac{}{}{5pt}{}{#1}{#2}}

% Command with 2 obligatory arguments (num and denom) and one optional argument (line width)
\newcommand{\myVariableThickFrac}[3][0.4pt]{\genfrac{}{}{#1}{}{#2}{#3}}

\begin{document}

%\genfrac{left-delim}{right-delim}{thickness}{mathstyle}{numerator}{denominator}

$$\genfrac{}{}{5pt}{}{\text{num}}{\text{demom}}$$

$$\myThickFrac{\text{num}}{\text{demom}}$$

$$\myVariableThickFrac{\text{num}}{\text{demom}} = \myVariableThickFrac[3pt]{\text{num}}{\text{demom}} = \myVariableThickFrac[5pt]{\text{num}}{\text{demom}}$$

\end{document}


Question to the experts here. I don't know why the line width also influences the spacing so much. And I do not know that to do with the remaining arguments {left-delim}, {right-delim} and {mathstyle} (but that is not important here as it seems).

• \genfrac is from the very famous amsmath package.
• The package mathtools that I use here is an extension package to amsmath
• mathtools loads amsmath automatically.
• See mathtools vs amsmath for more details.

From the amsmath manual

• The other statement (about mathtools) is not quite right. mathtools loads amsmath and provides additions to it. Nothing in this example needs mathtools, amsmath is enough – daleif Apr 6 '17 at 11:14
• I was simplifying on purpose. And I wanted to encourage to use mathtools :). I'll update the answer -- feel free to correct me again. – Dr. Manuel Kuehner Apr 6 '17 at 11:15
• @daleif I updated the answer and added another question :(. Maybe you can jump in. – Dr. Manuel Kuehner Apr 6 '17 at 11:24
• Me again, I just figure it that all lines are bold lines of box, all fraction lines, equal signs are also little bit bold, not bold with /textbf but bolder than mine. Does anyone has solution for that? :) – Ana Leko Apr 6 '17 at 12:24
• the width of the fraction lines is a parameter in the font dimensions (in .tfm files). it is a misfeature in tex that the space above and below the fraction line uses the same dimension parameter. this is a side effect of the very limited memory available when tex was created, and it's too late to change now.if .tfm files are being used for fonts. i don't know whether the limitation has been addressed in xetex or luatex. – barbara beeton Apr 6 '17 at 13:45