What 𝑓 means
It is a math-italic f whose meaning depends on the formula.
In formulas, a lone italic letter usually names one variable. In 𝑓(𝑥), 𝑓 names a function and 𝑥 is the input; the surrounding expression tells you which reading fits.
Leonhard Euler used f(x) to denote a function in 1734, but the familiar notation took time to catch on. That history belongs to function notation; today, 𝑓 lets plain text preserve mathematical italics when the style matters in an equation.
In equations, 𝑓 is mathematical notation; for italic prose, format ordinary f instead.
Part of the collection
What it means when someone sends it to you
2 readingsA single variable; its value depends on the equation.
Don't confuse it with
1
Combination ideas
1Questions people ask
1Does 𝑓 turn into f when normalized?
Yes, under NFKC or NFKD: compatibility normalization maps 𝑓 to ordinary f, removing its mathematical style. NFC and NFD preserve the distinction.
More like this
11
How to type or find 𝑓
- Search it as
- f(x) · function f · f variable · math italic f · Unicode f
- Shows up in
- Anything that takes text · its shape is whatever your font draws
𝑓\1D453𝑓; that numeric character reference represents this exact character.$f$ renders an ordinary italic variable; \mathit{f} requests math italics explicitly. These format f rather than necessarily emitting the 𝑓 character.Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.