# How to boldify math without changing font style

I want to boldify math equations and symbols with out changing the actual font.

I tried the following, but I am not getting satisfactory results.

      a=f \equiv 2 \mod 4
\bm{a = f \equiv 2 \mod 4}
\mathbf{a = f \equiv 2 \mod 4}
{\boldmath $a = f \equiv 2 \mod 4$}


The output for the above tags is as follows

I want my equation like the third line with fully bold, but with preserved alphabet font as in line 1.

\bm is not boldifying the entire equation, and \boldmath is not boldyfying at all. How can I preserve alphabet font using \mathbf?

• First of all: Don't use $$....$$. That's deprecated syntax. Use $...$ instead. Second: Don't post fragments only. Third: \boldmath must be used outside of math mode ('must', because there's a warning!) – user31729 Jun 14 '16 at 10:14
• Third: Yeah true, even though I use \boldmath outside math, it is not boldifying the equation. – hanugm Jun 14 '16 at 10:19
• \bm {...} is bold for me, as well as \boldmath – user31729 Jun 14 '16 at 10:19
• For me, it is working on some pages, and not working on some pages, working for some part of the equation and not working for remaining part of the equation. So, i need to know the way of using [ \mathbf ] without changing font. – hanugm Jun 14 '16 at 10:26
• So, i need to know the way of using \mathbf doesn't really have an answer \mathbf is a font changing command that changes the font of (only) letters to bold upright roman. What you want is \bm which will select bold for all symbols for which you have a bold font or \boldmath if you want the entire expression bold, again assuming you have bold math fonts. If it is not working for you, post a proper example that people can test/debug. – David Carlisle Jun 14 '16 at 11:03

You need \bm or \boldmath, not \mathbf

\documentclass{article}
\usepackage{amsmath}
\usepackage{bm}

\begin{document}

$a=f \equiv 2 \mod 4$

$\bm{ a=f \equiv 2 \mod 4}$

{\boldmath $a=f \equiv 2 \mod 4$}

\end{document}


Of course the bold symbols need to exist, not all font sets include bold.

• What causes the difference in spacing? – Manuel Jun 14 '16 at 11:14
• @Manuel \bm is a bold region in a math expression using the font parameters of the (non bold) \textfont2 but \boldmath sets up the entire math parameters based on the fontdimens in the bold \textfont2 – David Carlisle Jun 14 '16 at 11:16

For me, there's no difference between \bm and \boldmath regarding the regular symbols and numbers, \mathbf switches the font indeed and the spacing is different:

\documentclass{article}

\usepackage{mathtools}
\usepackage{bm}

\newcommand{\mathcontent}{%
a=f \equiv 2 \mod 4%
}

\begin{document}
$a=f \equiv 2 \mod 4$
$\bm{a = f \equiv 2 \mod 4}$
$\mathbf{a = f \equiv 2 \mod 4}$
\boldmath
$a = f \equiv 2 \mod 4$ \unboldmath

Now all using \verb!\boldmath!

\boldmath

\fboxsep=0pt
\fbox{$\mathcontent$}

\fbox{$\bm{\mathcontent}$}

\fbox{$\mathbf{\mathcontent}$}

\end{document}