[Tex/LaTex] The history behind the broken epsilon


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

enter image description here

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?


\texttt{\textbackslash{}varepsilon}     & \(\varepsilon\)   \\
\texttt{\textbackslash{}epsilon}        &\(\epsilon\)           

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.