[Tex/LaTex] The history behind the broken epsilon

fontssymbols

In LaTeX, there are two epsilons: \varepsilon and \epsilon.

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When I see the second one used in mathematics texts, I consider it a typo, because the first one corresponds to what is used in the majority of texts but also what is used when writing maths by hand. By personal taste, I prefer the first one and consider it the correct version.

Be that as it may, whichever is the correct one, there seems to be no need to have two. Hence my question:

Why are there two versions or epsilons? Why does the command \epsilon not get compile into the first version?

\documentclass{article}
\usepackage{amssymb}

\begin{document}
\begin{tabular}{ll}
\texttt{\textbackslash{}varepsilon}     & \(\varepsilon\)   \\
\texttt{\textbackslash{}epsilon}        &\(\epsilon\)           
\end{tabular}
\end{document}

Best Answer

From Wikipedia:

The lowercase version has two typographical variants, both inherited from medieval Greek handwriting. One, the most common in modern typography and inherited from medieval minuscule, looks like a reversed "3". The other, also known as lunate or uncial epsilon and inherited from earlier uncial writing,[1][2] looks like a semicircle crossed by a horizontal bar. While in normal typography these are just alternative font variants, they may have different meanings as mathematical symbols. Computer systems therefore offer distinct encodings for them.[1] In Unicode, the character U+03F5 "Greek lunate epsilon symbol" (ϵ) is provided specifically for the lunate form. In TeX, \epsilon (\epsilon\!) denotes the lunate form, while \varepsilon (\varepsilon\!) denotes the inverted-3 form.

Most math texts I saw use \epsilon but it is convenient at times to have a variant.

Related Solutions

[Tex/LaTex] \varepsilon vs. \epsilon

Historically there has been a lot of confusion over the two forms, (the situation with \phi and \varphi is similar but even more confused as at one point Unicode swapped the reference glyphs). I added a special section about epsilon to the XML/HTML entities spec

http://www.w3.org/2003/entities/2007doc/#epsilon

The situation in TeX is no different really, different communities used different forms of epsilon and it is rather arbitrary which one gets which name. Unicode (now) calls the curly epsilon "GREEK SMALL LETTER EPSILON" (ε) (this is a textual Greek letter rather than a math alphabetic symbol) and the symbol that TeX traditionally assigns to \epsilon is called GREEK LUNATE EPSILON SYMBOL (ϵ) the "symbol" being a hint that this is intended as a mathematical character rather than a textual Greek letter.

From Wikipedia:

The lowercase version has two typographical variants, both inherited from medieval Greek handwriting. One, the most common in modern typography and inherited from medieval minuscule, looks like a reversed "3". The other, also known as lunate or uncial epsilon and inherited from earlier uncial writing, looks like a semicircle crossed by a horizontal bar. While in normal typography these are just alternative font variants, they may have different meanings as mathematical symbols. Computer systems therefore offer distinct encodings for them. In Unicode, the character U+03F5 "Greek lunate epsilon symbol" (ϵ) is provided specifically for the lunate form. In TeX, \epsilon (ϵ) denotes the lunate form, while \varepsilon (ε) denotes the inverted-3 form.

[Tex/LaTex] Wrong Math Symbols – epsilon, varrho

Some fonts change not only the text font, but also the math font. This is the case with mathptmx. It is possible to grab a single symbol from another font though: