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I am using the normal \frac in display mode (\begin{equation}). This happens whether I'm using align, or double $, or whatever else.

This looks weird, right? Especially the numerator being so far away from the line.

Example

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    Welcome to TeX.SX. When you post a question, please provide a "Minimal Working Example" (MWE) that starts with \documentclass, includes all relevant \usepackage commands, ends with \end{document} and compiles without errors, even if it does not produce your desired output.
    – Sandy G
    Sep 15, 2022 at 1:20

1 Answer 1

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This looks weird, right?

No, it looks just fine.

Why-type questions are frequently nearly impossible to answer. However, for the case at hand, it's rather straightforward to provide an excellent reason for why TeX's default settings for placing the numerator and denominator of \frac are actually just fine. For instance, consider the output of

\documentclass{article}
\usepackage{amsmath} % for '\tfrac' and '\text' macros
%% Just for demonstration purposes; please don't do this at home:
\newcommand\ttfrac[2]{\tfrac{\textstyle #1}{\textstyle #2}}

\begin{document}
\[
  \frac{\sigma}{\epsilon} \frac{ky}{lz} \quad\text{vs.}\quad
\ttfrac{\sigma}{\epsilon} \frac{ky}{lz}
\]
\end{document}

enter image description here

In my view, the only typographically reasonable way to typeset the double fraction expression is to place \sigma on the same baseline as ky and to place \epsilon on the same baseline as lz, as is shown on the left in the screenshot above. Conversely, it would be a typographical disaster to move \sigma down a bit and/or to raise \epsilon a bit, as is shown on the right.

If you examine the output of \frac{ky}{lz} closely, you'll notice that TeX places the numerator term ky such that there's just a bit of "breathing space" between the lower edge of the letter y and the fraction line. Ditto for the fraction line and the upper edge of the letter l in the denominator.

Finally, if you simply cannot stand the "look" produced by \frac{\sigma}{\epsilon}, I'd like to suggest that you employ inline-style fraction notation instead:

\begin{equation}
E = \sigma / \epsilon \,.
\end{equation}

enter image description here

This should be all the more acceptable as you have $k=F/x$ right on the next line.

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    +1 for "don't do this at home" :-) One typo: "to raise \sigma a bit" should be "to raise \epsilon a bit".
    – campa
    Sep 15, 2022 at 8:42
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    +1. I believe that good examples are \frac{x}{y}+\frac{y}{x} and \frac{a}{b}+\frac{b}{a}
    – egreg
    Sep 15, 2022 at 8:50
  • @campa - Thanks! Fixed the typo.
    – Mico
    Sep 15, 2022 at 12:05
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    I had a feeling that I was the problem. Ok, thanks for this answer Sep 16, 2022 at 0:18

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