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 does outward facing rectangle brackets mean?

I recently saw this notation being used in the statement of a theorem of De Lellis and Szekelyhidi: The first sentence of the theorem says: Let $\Omega$ be an open ball in $\mathbb{R}^n$, $T>0$, and $\overline{e}$ a uniformly continuous function…
Ltoll
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Quote about difficulties doing multiplication/division prior to Arabic notation

On pages 61-62 of Code Complete, 2nd edition, there is this quote about Arabic notation: By relieving the brain of all unnecessary work, a good notation sets it free to concentrate on more advanced problems, and in effect increases the mental power…
klementine
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Difference between $\mathop{\text{div}} \vec x$ and $\vec \nabla \cdot \vec x$?

I often see the following notations for the divergence in theoretical Physics: $$ \mathop{\text{div}} \vec x \qquad \left\langle \vec \nabla, \vec x \right\rangle \qquad \vec \nabla \cdot \vec x $$ Similarly, $\mathop{\text{curl}} \vec x$…
Martin Ueding
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Notation for element of an ordered tuple?

When $X$ is a set, we can write: for all $x\in X$ ... But say that $X=(a, b, c, ... ,n)$. I.e. an ordered tuple. Is it standard notation to still say the following? for all $x\in X$... It might be confusing because if you interpret it as a…
user56834
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What does $3n$ mean in set builder notation form?

what does $2n$ or $3n$ mean? e.g.: $P= \{x : n \in \mathbb{N}, x = 3n, n< 3\}$ What does it mean? Im still a grade 7. Dont judge me
Mutants Genetic
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What does Wolfram's $n_{\#1}(1)$ mean?

What does Wolfram's $n_{\#1}(1)$ mean in the answer here? The input is, in code, |-4+8cos^2(α)+8cos^2(β)+4cos^2(β-α)|=1. I haven't got a clue.
Shaun
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Mathematical notation of substring

Let $\{a_1,a_2,\dots,a_n\}$ be an ordered set. Is there any established mathematical notation for the first $k$ (resp. last $k$ ) elements of this ordered set? This corresponds to the computer science equivalent of "substring". Thanks.
yoyostein
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What does this mathematical notation mean?

Please excuse this simple question, but I cannot seem to find an answer. I'm not very experienced with math, but I keep seeing a notation that I would like explained. The notation I am referring too generally is one variable m floating over another…
turtle
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Notation: What's $]a,b[$

Possible Duplicate: Question about set notation Suppose we have that $\ f:]a,b[\rightarrow\mathbb{R}$. What is $]a,b[$? I know what $[a,b]$, $(a,b)$, $[a,b)$ are. I would usually google but I don't know what keyword to use. Let me know if this…
Jase
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How to know what the letters mean in math formulas?

For example, see this Wikipedia section on Newton's laws of motion: Newton's Second Law states that an applied force, $\mathbf F$, on an object equals the rate of change of its momentum, $\mathbf p$, with time. Mathematically, this is expressed…
user353885
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Is There a Mathematical Symbol For Mutable & Immutable values?

As per above, is there a symbolical way of identifying a mutable value or an immutable value? As an example, in my notes, I want to denote the value 'Pi', 'Adam' as immutable, is there a symbol to represent an immutability of a value?
Kayote
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How to better denote the result of ifelse (D>C,C/D,D/C) mathematically?

The absolute value allows me to denote the difference between A and B regardless of which one is bigger, like so: $|A-B|$ or abs(A-B) in e.g. R. I'm trying to correctly denote a formula where i do the same with division of two positive numbers (say,…
Marloes Eeftens
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What’s the difference between equals signs ≈, ≅, and ≃?

My professors have seemed to use $≅$ and $≈$ pretty interchangeably to indicate that something is nearly equal to something else, and I just became aware of $≃$. When should we use one of these instead of the other? And, maybe more illustratively,…
Lucas
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The matter of signs in multiplication

I was browsing through the non-mandatory tasks on my college's website and I stumbled upon one which cracks my head quite a bit. It goes as follows: Prove why multiplying two numbers with different signs gives us a negative number while…
Straightfw
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How to express "$a \neq b \neq c \neq d$" correctly?

I would like to simply say "$a, b, c, d$ are all different" by mathematical notation. If I want to write all equal, then I can write $a = b = c = d$. However, if I write $a \neq b \neq c \neq d$, that does not cover $a \neq c$ and $b \neq d$…
padawan
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