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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What is the meaning of $e^{int}$ notation

I have a question and I have a definition $\{\varphi_n(t)=\frac{1}{\sqrt{2\pi}}e^{int}\}$.I know that $n\in \mathbb Z$ for this question. does int means integer? I couldn't find any reference with a web search.
havakok
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What is $\circeq$ used for?

I was looking for a way to put 'des' over the equals sign in latex and stumbled upon this symbol $\circeq$ What are mathematicians using it for?
Hennadii Madan
  • 163
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Question about math symbol $\bigsqcup$

Can someone tell me what this symbol means? $\bigsqcup$
WacDonald's
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Formal notation for a required statement

Is there a formal notation to distinguish an equality that is a true statement, e.g., [...] and hence, $$ x = x^2 - 1 $$ [...] from a demand, e.g., [...] so we require $$ x \stackrel{!}{=} x^2 - 1 $$ [...] ? The same thing could…
Nico Schlömer
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Notation for equivalent equations

What is the notation for showing that equations are equivalent by rearranging terms? For example, for the arc length formula: $$s=r\theta$$ I sometimes solve for $r$ and write it as $$r=\frac{s}{\theta}$$ When I show my work, I usually write this…
GamrCorps
  • 220
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What is a good notation for an “even falling factorial”?

It has been suggested to me that I use this notation: $$ \lfloor n \rfloor_2 = 2 \left\lfloor \frac n 2 \right\rfloor = \text{“even floor of $n$''} = \text{largest even integer}\le n. $$ I also want to write about an “even falling factorial” that,…
Michael Hardy
  • 1
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How can I calculate the number with"e"?

If here e is Euler then it is 2.718... but it couldn't be, the number being smaller every rows. 0.000227202114952789 0.000179517720456525 0.000141841161842193 0.000112072029109881 8.85507390497816e-05 6.99660160393339e-05 …
doci
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Plot a single point on number line in interval notation

For example, I want to plot the solution set $\{3\}\cup (2, \infty$). How do I represent 3 as a single point?
questioner and answerer
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Notation: Set where function is positive

Given some function $f: X \to \mathbb{R}$ from some space $X$ to the reals. I have sometimes seen the notation $\{f > 0\}$ used to denote the set $\{x \in X : f(x) > 0 \}$. Is this a common/usual notation? I would like to use the shorter one because…
Loreno Heer
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Correct notational use of $:=$

Suppose I use the notation $:=$ to define some symbol the first time it is introduced, e.g. $A:=\Im(f+f^2)$. If later on I make use/remind the reader of the symbol definition, e.g. $A=\Im(f+f^2)=\ldots$, should I use the notation "$:=$", or simply…
GFR
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Notation (or Name) of the function which is $0$ at $x=0$ and $1$ otherwise

Is there a traditional notation or name of this function: $$ \epsilon (x) = \begin{cases} 0 & \textrm{ if }x = 0 \\ 1 & \textrm{ if }x \neq 0 \end{cases} $$ I know one can use Indicator function $1_{A}(x)$ for $A = \mathbb{R} - \{0\}$, but I still…
user565739
  • 279
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When to use the $\equiv$ symbol (such as in $5^{6}$ $\equiv$ 1 mod 7) vs =

Can anybody explain why we would use the $\equiv$ symbol in the statement $5^{6}$ $\equiv$ 1 mod 7 ? I understand the $\equiv$ symbol means equivalence, but it seems like it would be more appropriate to use the = symbol.
User
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Summations and integrals with no upper limits

I've seen expressions like: $$\sum\limits_{i} f(x)$$ And $$ \int\limits_\mathbb{R}f(x)dx $$ What does it mean that they have no upper limits?
YoTengoUnLCD
  • 13,384
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Is there a standard notation for the product from right to left?

I am considering a product of the matrices $(A_i)_{1\leq i\leq n}$ in reverse order $$P=A_nA_{n-1}\dots A_1,$$ and I was wondering if there was a standard notation for it, like $\overleftarrow{\prod}$ or $\prod^R$... Thanks
Tom-Tom
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What does a single-line superscript left arrow mean?

I'm pretty sure it's a limit but I haven't been able to find any page explaining this notation (see below). It's from a paper on block maxima. 3 out of 5 occurences: $V=(-1/logF)^\leftarrow$ (p.4) $x_n=F^\leftarrow(1-p_n)$ (p.7) $k_0^{(i)}\sim…
Richard Löwenström
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