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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Notation: "$+$" exponent sign

I'm following this paper and came across some notation that I don't know; I've tried a number of queries such as "power to the plus", "plus exponent" etc but can't seem to find anything: From page 4: $\text{sign}(\beta_j)(|\beta_j| - \gamma)^+$ The…
tmakino
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Mathematical formal notation of a dictionary

I was wondering how to express a dictionary or associative array (as known in programming) formally in mathematical notation. A dictionary is basically a set of ordered pairs of keys and values, but each key must appear only once. Now, if $K$ is the…
Hyperboreus
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Can someone identify this math font?

I'm doing my master's thesis and trying to find a good font for math symbols and formulas. I would like to use the following font style: Can anyone recognize this? How to get X the way it is in this formula etc. in Word 2007? =)
jjepsuomi
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What symbol should I use for nonnegative real numbers

I know that positive real numbers can be denoted in the following way: $$ \mathbb{R}^{+} = \{x \in \mathbb{R}: x>0\} $$ I also encounter this symbol: $$ \mathbb{R}^{>0} = \{x \in \mathbb{R}: x>0\} $$ My question is: How can I denote nonnegative…
MMM
  • 751
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Subscript in maximum notation

My question is concerning a maximum notation. I have a $3\times 3$ matrix: $$Q=\begin{bmatrix}-3&2&1\\1&-2&1\\0&1&-1\end{bmatrix},$$ where $q_{ii}$ = $-\sum_{i \neq j} q_{ij}$. Let $\mu = \max_i(-q_{ii})$. I am unsure what the maximum refers to,…
EGSMIB
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Deciding on mathematical notation

I am currently collecting all the small pieces of independent mathematics I've done over the past year or so, a lot of which is calculus. I have lots of integrals and for the most part, I just call them $I$ or $I(a)$ if there is some variable…
Joshua Farrell
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Mathematical Notation to Represent Cumulative Sum

If I have a vector $x$ $$ x = [x_1, x_2, x_3, \ldots, x_N]$$ Is there any proper mathematical notation that best represents the cumulative sum? $$ y = [x_1, x_1+x_2, x_1+x_2+x_3, \ldots, x_1+x_2+x_3+\ldots+x_N]$$
slaw
  • 365
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What is $\left|\bigcup\limits_{n=0}^{10}\{n\}\right|$ supposed to be?

What "11" on this clock is supposed to be? it looks like the union symbol but I don't get it.
Mohannad Maklad
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When do I write $\sin(x)$ and when $\sin x$?

I sometimes see $\sin x$ and sometimes $\sin(x)$. Are the parenteses needed since the sine is a function or is it more an operator that can be premultiplied to the variable? Or are people just lazy?
Martin Ueding
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What is the meaning of $\mathbb{N_0}$?

What is the meaning of $\mathbb{N_0}$? To put it into context, I have in my notes, $f^{(k)}$, $k \in \mathbb{N_0}$ is a continuous function on $[-\pi, \pi]$. How is it different to saying $k \in \mathbb{N}$?
Al jabra
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Notation for infinite product in reverse order

This question is related to notation of infinite product. We know that, $$ \prod_{i=1}^{\infty}x_{i}=x_{1}x_{2}x_{3}\cdots $$ How do I denote $$ \cdots x_{3}x_{2}x_{1} ? $$ One approach could be $$ \prod_{i=\infty}^{1}x_{i}=\cdots…
Uday
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Does this math formula with $1/PI\begin{cases}^\infty_{-\infty}\end{cases}$ mean anything?

I happened upon an image on the Internet (source: news.com.au) and I wondered whether the math on the chalkboard means anything. Using Google's image search, I found three other related images. (source: nees.org) Piecing together the math from…
Tim Thayer
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Blackboard bold, Bold, Fraktur, and Reserved Variable.

There seems to be an arbitrary choice of how one would want to represent the set of all real numbers. Most commonly, I've seen $\Bbb{R}$, followed by $\textbf{R}$, then by a reserved variable $R$, then, only once or twice, by $\mathfrak{R}$. I…
Conor O'Brien
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Reading equations: Upside down A

what does this equation mean? I´m really bad in reading those, so if somebody explained it, I would really appreciate. $f_i(x,y)\ge 0\quad\forall i\{0,1,2\}$
dan
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"Evaluated at" or "at" notation

Normally a variable that is a function another variable would be represented as in the following fashion: $ V(t) $ (voltage as a function of time). However, my engineering professor (who also wrote the textbook) likes to use the vertical bar…
bongbang
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