What it means
The fifth Greek letter, printed in two shapes, ε and ϵ, which mean the same. It stands for a small positive number, the error term in a regression, strain in mechanics, and with a subscript zero for the permittivity of free space.
Read aloud in real formulas
y = β₀ + β₁x + ε
Aethel says
y equals beta sub zero plus beta sub one x plus epsilon
the error term
∇ · E = ρ / ε₀
Aethel says
the divergence of E equals rho over epsilon naught
ε₀, the permittivity of free space
|x − a| < ε
Aethel says
the absolute value of x minus a, is less than epsilon
x lies within ε of a
Typing it
- LaTeX
- \varepsilon, \epsilon
- Unicode
- U+03B5, U+03F5, U+0395
Formulas that use it
Questions
How do you pronounce epsilon (ε)?
It is said “epsilon”, roughly EP-sih-lon (UK also ep-SY-lun).
What does ε mean in maths?
The fifth Greek letter, printed in two shapes, ε and ϵ, which mean the same. It stands for a small positive number, the error term in a regression, strain in mechanics, and with a subscript zero for the permittivity of free space.
How do you type ε?
In LaTeX, write \varepsilon, \epsilon. Its Unicode code point is U+03B5, U+03F5, U+0395.
What is ε often confused with?
It is easy to mistake for ∈, which means "is an element of" and is a different symbol.