What does mean number mean

How to Find the Mean

The mean is the average of the numbers.

It is easy to calculate: add up all the numbers, then divide by how many numbers there are.

In other words it is the sum divided by the count.

Example 1: What is the Mean of these numbers?

The Mean is 8

Why Does This Work?

It is because 6, 11 and 7 added together is the same as 3 lots of 8:

It is like you are «flattening out» the numbers

Example 2: Look at these numbers:

3, 7, 5, 13, 20, 23, 39, 23, 40, 23, 14, 12, 56, 23, 29

The sum of these numbers is 330

There are fifteen numbers.

The mean is equal to 330 / 15 = 22

The mean of the above numbers is 22

Negative Numbers

How do you handle negative numbers? Adding a negative number is the same as subtracting the number (without the negative). For example 3 + (−2) = 3−2 = 1.

Knowing this, let us try an example:

Example 3: Find the mean of these numbers:

The mean of the above numbers is 2.4

Here is how to do it one line:

Mean = 3 − 7 + 5 + 13 − 25 = 125 = 2.4

Try it yourself!

Advanced Topic: the mean we have just looked at is also called the Arithmetic Mean, because there are other means such as the Geometric Mean and Harmonic Mean.

What do the numbers in a man page mean?

I’m wondering what the significance of the numbers in the parentheses are, if they have any.

8 Answers 8

The number corresponds to what section of the manual that page is from; 1 is user commands, while 8 is sysadmin stuff. The man page for man itself ( man man ) explains it and lists the standard ones:

Note that the section can sometimes include a subsection (e.g., the p in 1p and 3p above). The p subsection is for POSIX specifications; the x subsection is for X Window System documentation.

The history of these section numbers goes back to the original Unix Programmer’s Manual by Thompson and Ritchie in 1971.

The original sections were

konqueror also describes non-standard sections: (thanks to @greg0ire for the idea)

From the man manpage:

These are section numbers. Just type man man or open konqueror and type man://man and you’ll see what are these sections.

Often, a man page is referenced via suffixing it with the section enclosed in parentheses, e.g.:

This style has two main advantages:

Man pages are organized in sections, e.g. Section 1 includes all user command man pages, Section 2 all man pages for the system calls, Section 3 is for library functions etc.

On the command line, if you don’t explicitly specify the section you get the first matching man page, in the default section traversal order, e.g.:

displays BASH_BUILTINS(1) on Fedora. Where

displays the man page for the read() system call.

(the sections ending with p are POSIX man pages)

A tree update function:

3 Answers 3

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i)+1 (flip bits, then add 1).

In case anyone wanted a more general proof as well,

Assume x has the format a10 k (meaning here, some bitstring a, followed by a 1, followed by k zeroes).

-x is (by definition) the same thing as

So we are left with only that single rightmost 1 that we assumed existed.

This two functions are a modified implementation of a Binary index tree (Fenwick tree) data structure.
Here is two pictures to supplement MikeCAT’s answer showing how i variable updates for different values.

The «get» function:
For assume max value in of input in function is 15 for simplicity of representation.

A node with number t in on it represents tree[t] in the tree array.
If you call get function for i the returned value is sum of tree[i] plus sum of all tree array elements that their index in the array is a parent of i in the picture, except zero.
Here are some examples:

Numbers on the labels on nodes in the above picture has the property that each node’s parent is that node label minus the least significant one 1(explained very well on @MikeCAT answer)
The «update» function:
For simplicity of picture, let assume that the max length of the tree array is 16.
The update function is little bit trickier.

It adds val to tree[i] and all tree elements that their index is parent of the node with label i in the picture.

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Многозначное слово «mean»

Posted on 2014-08-06 by admin in Всякая всячина // 20 Comments

Английское слово «mean» относится к числу самых противоречивых, поскольку у него много значений, и притом, абсолютно разных. К тому же, слово «mean» может выполнять функции разных частей речи.

Существительное mean

В качестве существительного mean означает «середина», «средняя величина, среднее число»:

Прилагательное mean

В качестве прилагательного mean имеет множество интересных значений, — судите сами.

1. Для обозначения средней величины, например:

2. Прилагательное mean может означать «плохой, посредственный», и это, в основном, относится к способностям человека:

3. Если человек скуп или редкий скряга, о нем скажут:

4. О скудной пище или убогом жилье, нищенском, бедном одеянии и т.д. мы скажем :

5. Слово mean просто незаменимо, если нужно подчеркнуть, что кто-либо является низким, подлым, нечестным, презренным человеком:

6. Прилагательное mean указывает на низкое происхождение:

7. В разговорном английском «mean» означает «придирчивый, мелочный, злобный, неприветливый».

Между прочим, «злая собака» также будет «mean dog».

8. Поразительно, как mean может одновременно означать и плохое, и хорошее, относиться не только к подлому человеку, но и к совестливому и смущающемуся:

Глагол mean (meant)

В качестве глагола mean также имеет значения, просто необходимые нам в разговорной речи — “иметь в виду, намереваться, подразумевать, иметь значение”:

What does the number in parentheses shown after Unix command names in manpages mean?

What do the numbers in parentheses (Brit. «brackets») mean?

7 Answers 7

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It’s the section that the man page for the command is assigned to.

These are split as

Original descriptions of each section can be seen in the Unix Programmer’s Manual (page ii).

In order to access a man page given as «foo(5)», run:

The section the command is documented in the manual. The list of sections is documented on man’s manual. For example:

This is useful for when similar or exactly equal commands exist on different sections

The reason why the section numbers are significant is that many years ago when disk space was more of an issue than it is now the sections could be installed individually.

Many systems only had 1 and 8 installed for instance. These days people tend to look the commands up on google instead.

As @Ian G says, they are the man page sections. Let’s take this one step further though:

2. man

Let’s imagine you are Googling around for Linux commands. You find the OPEN(2) pg online: open(2) — Linux manual page.

3. man intro

This search order is intentional, as the man man page explains:

Why did they choose this order? I don’t know (please answer in the comments if you know), but just realize this order is correct and intentional.