# Line spacing with inline formula including fraction

I have a fraction in an inline formula as can be seen in the picture. \dfrac from the amsmath package was used. (This is article class with 14pts and linespread 0.9.)

Though the space between the line including the formula and nearby lines are expanded, the space between the denominator of the fraction and the next line is still smaller than the one between other all-text lines.

How can I expand the space so that equal space is guaranteed? (I don't want to make the fraction part smaller.)

I already tried abovedisplayskip and belowdisplayskip, but they seem to work only in \display environment.

I may find a command that works only for specific lines, but I want this spacing applied to the entire document where there is an inline formula with fractions.

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That expression is far too big for inline, why don't you want it as display math $...$ ? – David Carlisle Feb 6 '13 at 17:19
You may want \setlength{\lineskip}{2pt} or something more (default is 1pt). But really such a big object should be in a display. The article class doesn't have a 14pt option. – egreg Feb 6 '13 at 17:22
Don't use \dfrac for inline-math fraction expressions; use \tfrac instead. Alternatively, use the "slash" notation, i.e., something like $\Pr\{...\}/\Pr\{...\}$. – Mico Feb 6 '13 at 17:32
@Mico: Not that \frac and \tfrac are the same in inline-math (unless they're used inside a fraction ...). – Hendrik Vogt Feb 7 '13 at 20:18
@Mico: Of course, I fully agree, \dfrac in inline-math shouldn't be used (except maybe in something like one-line exam problems). – Hendrik Vogt Feb 7 '13 at 20:34

Such a big formula doesn't find its place in line; you could set (maybe locally) \lineskip to 2pt instead of the default 1pt:

... end of the previous paragraph.

\begingroup
\setlength{\lineskip}{2pt}

The paragraph with the big $\dfrac{\Pr(X-a)}{\Pr(X-b)}$ which
spoils the appearance of the page.

\endgroup


(Note the blank line before \endgroup to end the paragraph.)

However, the best way to typeset large formulas is to display them:

The paragraph with the big
$\frac{\Pr(X-a)}{\Pr(X-b)}$
which doesn't spoil the appearance of the page and

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it appears that the last line before the line with the fraction contains no descenders. thus it has zero depth.

add a \strut (a zero-width box with the depth of a parenthesis) to artificially provide the depth you need to avoid this effect. don't put a space before the \strut.

regardless, everyone who says that displaystyle fractions shouldn't be used in text is correct; this is a bad thing.

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