[Tex/LaTex] Ugly spacing around f in math mode

math-modespacing

My paper contains many math expressions like $abcde$ or $abdefv$ . Unfortunately, the latter looks very ugly, particularly in regards to the spacing around the f. In particular, there is a significant amount of space around the f which is not present around the other letters.

Is there a method to make that spacing tighter?

Note: Joseph Wright suggested using \! to get a negative thin space. This does seem to help. But I'm still a bit curious as to why the problem occurs at all. For example, it looks fine in $acdfv$ before the f but not after. If anyone has some more details on why the spacing ends up as it does, please comment. Thanks.

Best Answer

For a detailed answer why this is happening you can read this answer of mine (shameless plug indeed): In short, the italic correction of the f has a great part in this. But the italic correction only explains the spacing after the f, not before. For this you have to look at the bounding boxes of the letters:

The first f is a text italic letter in its bounding box, the second one is math italic (in its bounding box together with its italic correction). As you can see, the text letter protrudes a bit to the left (and a lot to the right); the math letter has a tiny bit of white space in the left (and also in the right, because of the italic correction). For a bit more about the bounding boxes see this question of mine (another shameless plug :-)).

I first noticed the problem when typing $Vf$ , which doesn't yield a nice output. My resort is using $V\hspace{-0.1em}f$ instead (in a macro, of course), which I like much better. You could even use $V\!f$ , but this I find too narrow. Compare these three:

I would not encourage you to follow Caramdir's (now removed) suggestion to use $\mathit{Vf}$ since this uses a different font (text italic, not math italic). You can see quite clearly that the V is narrower (in other words, the angle at the bottom of the V is more acute):

If you use a different math font (like Euler), then the difference is even more noticeable.

(For a case where \textit could be a good solution, see this answer of TH.)

Related Solutions

[Tex/LaTex] Inline math spacing and varying interword spacing

There is some glue in \:, but not in \!: the first uses \medmuskip which is 4.0mu plus 2.0mu minus 4.0mu, the second \thinmuskip which is 3.0mu. To avoid the glue use only \! or, simpler, just \mkern:

Sample output

Second sample

\documentclass[a5paper]{article}
\newcommand{\md}{\ensuremath{M\mkern-9mu D}}
\begin{document}
a a a a a a a a a a a a a a a a a a a a a a $\md$ a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a

aaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaa $\md$ aaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaa aaaaaaaaaa aaaaaaaaaaa aaaaaaaaaaaaa aaaaaaaaaaaaa
aaaaaaaa

\clearpage
\hbox{aa aa $\md$ aa aa}

\hbox spread 10pt{aa aa $\md$ aa aa}

\hbox spread 20pt{aa aa $\md$ aa aa}

\end{document}

As 18mu = 1em this is much closer spacing than you ask for, use -2mu instead.

The numbers in my statements above come from:

\documentclass{article}
\begin{document}
\( \show\!\show\: \)
\showthe\thinmuskip
\showthe\medmuskip
\end{document}

which prints the following infomation in the log file:

> \!=macro:
->\mskip -\thinmuskip .
l.10 \( \show\!
               \show\: \)
> \:=macro:
->\mskip \medmuskip .
l.10 \( \show\!\show\:
                       \)
> 3.0mu.
l.11 \showthe\thinmuskip

> 4.0mu plus 2.0mu minus 4.0mu.
l.12 \showthe\medmuskip

As far as I can see, in standard latex, the glued skips \medmuskip and \thickmuskip, are only used around binary and relation symbols, and in the definition of \bmod.

[Tex/LaTex] Increasing vertical space after equation in paragraph with short previous line

You seem to want that \belowdisplayshortskip is set equal to \belowdisplayskip; the former is used if the line above the display is “short”. The parameters are set in \normalsize (and also in \small and \footnotesize). Just append the appropriate declaration.

\documentclass{article}
\usepackage{etoolbox}
\appto\normalsize{\belowdisplayshortskip=\belowdisplayskip}
% the following two are not strictly necessary
\appto\small{\belowdisplayshortskip=\belowdisplayskip}
\appto\footnotesize{\belowdisplayshortskip=\belowdisplayskip}

\begin{document}

The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the.
\begin{equation}
  \frac{a}{b}
\end{equation}
The paragraph continues here.
The paragraph continues here.
The paragraph continues here.

The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps.
\begin{equation}
  \frac{a}{b}
\end{equation}
The paragraph continues here.
The paragraph continues here.
The paragraph continues here.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the.

\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] Inline math spacing and varying interword spacing

[Tex/LaTex] Increasing vertical space after equation in paragraph with short previous line

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