Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I try to write math notes as clearly as possible. In practice, this means using letters and notation similar to what the reader is already familiar with.

A real function is often $f(x)$, an angle is often $\theta$, a matrix has size $m\times n$, and $i$ is often an index. The full theoretical list is long and complicated. For example, $\pi$ is very often a constant, but sometimes it's a variable for a permutation. Capital sigma $\Sigma$ can indicate summing a series, but it can also denote a matrix, as in the singular value decomposition. So things like context matter, and a great list would have to include more than just variable names. Another choice to make is how to write an inner product, for example.

Does such a list exist?

share|cite|improve this question
up vote 1 down vote accepted

If in doubt, use Wikipedia.

This gives a list of mathematical symbols and all the (widely-used) contexts in which they arise:

Another good list for letters (Roman and Greek) is:

This tells you what each letter represents in different branches of maths (and science).

Just for maths, there is:

Finally, there is,_science,_and_engineering.

share|cite|improve this answer
I think the Latin letters used math page is the closest to the list I was looking for. The Mathematical Notation book mentioned by @fred-kline also looks excellent. Thanks! – Tyler Jul 15 '14 at 18:15

In my own experience the letters $a,b,c,d,e$ are reserved for coefficients. $f, g, h$ are functions. $i,j,k$ are indices. (Sometimes $i=\sqrt{-1}$) $l,m,n$ are also indicies (and in particular natural numbers or integers)

$o$ isn't often used, since it can be confused with zero. Though it can be "little"-o for asymptotics.

$p,q$ are usually polynomials or rational functions or primes.

$r, s,t$ are real numbers, variables, or coefficients.

$u,v,w$ are variables used for coordinate transformations of the real variables $x,y,z$. Also $z,w$ are variables in complex analysis.

Capital $A,B$ and $M$ are matrices. $N$ is a natural number. $R$ is a radius or bound. $C$ is a constant. $T$ is a linear operator.

Obviously this depends on the field and person to a large extent. I have always found it amusing how difficult it can be to choose just the right letter for something. I get stuck when I am trying to use a letter for a function after $f,g,h$ are already taken.

share|cite|improve this answer
$p$ and $q$ are also often primes. – Nishant Jul 14 '14 at 13:40
Indeed. It's been a while since I did some number theory. – Joel Jul 14 '14 at 13:43

I just got: Mathematical Notation which is surprisingly comprehensive for such a thin book. It covers several mathmatical topics. It even has $\LaTeX$ examples. Edit: it even has conventions for notes and blackboards.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.