Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [notation]

Questions on the meaning, history, and usage of mathematical symbols and notation. Please remember to mention where (book, paper, webpage, etc.) you encountered any mathematical notation you are asking about.

Before asking a question on the site, please check if you can find your answer in Earliest Uses of Various Mathematical Symbols or the book A History of Mathematical Notations.

Alternatively, a textbook or paper usually takes the time to explain the notation they're using; please remember to mention where you've seen the notation you are asking about.

12848 questions
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Question about using the notation "$\pm$" to represent the answer briefly.

I saw this problem in the book with answer: Solve the equation $z^4+z^2+1=0$. The book gave the final answer as: $$z_1=\frac{1}{2}+ \frac{\sqrt{3}}{2}i, \quad z_2=\frac{-1}{2}- \frac{\sqrt{3}}{2}i,\quad z_3=\frac{-1}{2}+…
Aligator
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Common Notation for Sets or Spaces

Is there some good reference (website could be better) to know the meaning of symbols (generally used) for any "special" kind of sets or spaces like $\mathbb{R}^{2}_{\geq}$? I've looked up, without success, in: Enlightening Symbols: A Short History…
John M-D94
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What is the notation of the set of all tuples?

I have 2 mathematical objects $F_a$ and $F_b$ and I am interested in the set that contains $(), (F_a), (F_b), (F_a,F_b), (F_a,F_a), (F_b,F_b), (F_b,F_a), (F_a,F_a,F_a)...$ (all the ordered finite sequences composed of any amount of $F_a$s and…
Anne Aunyme
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Notation - meaning of mod(x,y)

Reading about AKS primality test I've encountered the expression $(x+1)^n \equiv x^n+1 \mod{(n, x^r-1)}$. What does the notation $x\equiv y\mod{(r,s)}$ mean in general? Is it simply $x \equiv y \pmod r\pmod s$?
GottlobtFrege
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fractions inside of a decimal?

$\frac{1}{3} = 0.333333.... $ $\frac{1}{3} = 0.33\frac{1}{3} $ I ran into this fraction-in-a-decimal notation in a course I'm helping somebody with. I have never seen this before, and google results simply yield "how to turn fractions to decimals"…
emragins
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Is there a character to depict a large number?

Does a symbol exist to depict an arbitrarily large, finite number?
somehume
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Symbol for the number of elements in a set

I would like to express below concisely and mathmatically TP is a set of real numbers $$C = \{ x \in TP : x > threshold \}$$ c_count = len(C) Basically, in English, I want to count the number of numbers in TP is greater than threshold
samol
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How do you write sigmoid function for matrices and vectors?

I would like to apply the sigmoid (logistic) function: $\sigma{(x)} = \frac{1}{1+e^{-x}}$ to a vector $\mathbb{R}^n$ or matrix $\mathbb{R}^{m × n}$. And the question is how to write this function for vectors/matrices. I need it for a scientific…
Vadim
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Can anyone explain the following slash notation?

This notation can be seen made use of in equation 1.5 of https://arxiv.org/pdf/1311.5200.pdf Roughly speaking, $$\left. I = \int f(z) \prod_a \frac{dz^a}{z-z_a} \middle/ d\omega \right.$$ where $$d\omega = \frac{dz^1 dz^2…
Dr. user44690
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Does the English word "entails" mean an implication or an equivalence?

It is my first time that I met the word "entails". In mathematical texts, one usually sees "if and only if", "implies" or "iff" which bear no ambiguity. In the following definition: Does "entails" mean "implies"? It certainly seems so. Also In one…
Martin Drozdik
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Complex math symbols, and definitions

I find it difficult to explain this because I'm not sure what is the correct term to use. Symbols such as the triple-bar-equal sign, and a few other symbols that I find difficult to describe. I was wondering if there was a list of symbols with…
alexyorke
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Why do certain notations differ around the world?

I've been wondering this ever since I started using internet for maths actively -- reading math books, this website and sites similar to this one. Sometimes I run into some notations that I'm not sure what they mean, or why are they used in a…
Lazar Ljubenović
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Creating a new math symbol?

I am working on a lemma that uses equivalence classes and $\equiv_{k}$ indicates that two sets are congruent mod $k$. Example: with $k=4$ there are $24$ possible sets, of which I only want to consider $6$ sets as congruent. I have an algorithm to…
Fred Daniel Kline
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Where does sum symbol end in an expression such as $\sum_{i=1}^n (a_i+b)^2 + \sum_{j=1}^m a_j$?

I am looking at the following equation: $$\sum_{i=1}^n (a_i+b)^2 + \sum_{j=1}^m a_j$$ I am not sure what the convention for the order of operations for this would be. Is it: $$(\sum_{i=1}^n (a_i+b)^2) + \sum_{j=1}^m a_j$$ or $$\sum_{i=1}^n…
sixtyfootersdude
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Notation for $n$-dimensional intervals

I have a function that maps a number of reals to points where each of its dimensions is constrained to the same interval. I thought about writing it like so: $$f:\mathbb{R}^m\rightarrow (a,b)^n$$ Would this be correct?
overdisperse
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