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.

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Is $y'$ a valid notation for $f'(x)$?

In this context, let us say that: $$y=f(x)$$ I've seen both the notation $y'$ and $f'(x)$ being used. Are both correct?
user160601
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Notation question (factoral squares?)

Not sure whether factoral is even the right word to use in this context but I'm looking for how you write 'the sum of all the squares' eg 3 = 14 (3^2 + 2^2 + 1^2) 4 = 30 (4^2 + 3^2 + 2^2 + 1^2)
PerryW
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How to notate a set of point meeting a given condition?

How do you formulate the set of the n closest neighbours within the radius r of point P with proper mathematical syntax?
Simen Musæus
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Is the following use of indices correct?

Is the following use of indices correct? A vector $\langle x_i, x_{i+1},...,x_{i+k}\rangle$ is given. For every such vector a function is defined through $$\mu=\frac{\sum_{j=0}^k I_A(x_{i+j})}{k+1}\,,$$ where $I_A$ is the indicator function of some…
user145404
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Should random variables be italic or roman ($X$ or $\mathrm X$)?

I just recently learned that it is good style to write constants like Euler's number $\mathrm e$ and also functions and operators in roman letters while reserving italic letters for variables. Example: $\mathrm f(x)=x^2$. However, I wonder what…
Amarus
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Notation for a sum defined in terms of base 2

First acknowledging the helpful response to the earlier version of this sequence, I have found a complete expression for the sequence in closed form, and would be interested in improvements to the base 2 notation of the sum. Is there a standard form…
daniel
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If $V$ is a vector space, that what is $V^\mathbb{N}$?

Notation question (I believe the notes that I'm reading uses pretty common notation): Let $V $ be a vector space over a field $K$. What is $V^\mathbb{N}$? Is it a vector space of infinite dimensions? What are the elements of $V^\mathbb{N}$? Are they…
user2468
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Closed form for sequence of distributions

This sequence of distributions interests me and I am looking for an expression in closed form. We are looking at populations of size n!. For n=2, we divide the population in half, and assign to each half the property 2 and not-2 (I write 2'),…
daniel
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How should I signify the $y$ value of a given point

This is more of a aesthetics question than maths. But if I want to use the $y$ value of a given point $P$ in an equation how to I write this? I can't really show any working since I've just googled for an answer.
FraserOfSmeg
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Meaning symbol $\overline{\lim_{n\rightarrow \infty}}$

I found this symbol on a math book that I'm studying. It had never happened before. What does this mean? $$\overline{\lim_{n\rightarrow \infty}}$$
Mark
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What is meant by the double vertical line notation here?

What do the double vertical lines around $\vec i$ and $\vec j$ in this equation actually mean? $$ sim(i,j) = cos(\vec i, \vec j) = \frac{\vec i \cdot \vec j}{\lVert \vec i\rVert^2 * \lVert\vec j\rVert^2} $$
conorgriffin
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notation "interior to"

I am writing out some notes as review, and a thing I often say is "z is a point interior to C". I was wondering if there is a common shorthand to write this before I make one up for myself. C is a contour if that makes a difference
Rich Williams
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How to verify if an element is inside an ordered pair?

The notation to verify if an element belongs to a set is $e \in E$. But which notation should I use to verify if an element is part of an ordered pair? Is $a \in (a,b)$ valid (e.g., $1 \in (1,2)$)? Thanks!
user136598
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Is $\mathbb{Z}_+ = \{ 0, 1, 2, \dots \}$ or $\mathbb{Z}_+ = \{ 1, 2, \dots \}$?

Is there complete consensus on which of these is true?
user46234
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Notation for "all integers less than $n$"

Is there a short mathematical notation for all integers less than $n$ where $n$ itself is some integer? The only thing that comes to mind is $$\mathbb{Z} \cap (-\infty, n),$$ But this is pretty ugly and involves reals. Is there a better way to do…
Phonon
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