#Demo Article

_You can [see the source of this article](https://raw.githubusercontent.com/e-maxx-eng/e-maxx-eng/master/src/demo-article.md) to better understand formatting features._

The header is made of line starting with `#` (hash) symbol. Note that also we need to add a magical `?title` comment which

defines the title of the resulting HTML page for browser and search engines. It could be placed anywhere on a separate line

in the form:

<!--?title Demo Article-->

Text is written in paragraphs, separated with empty lines. Line breaks in paragraphs are regarded as ordinary spaces. If you

add a couple of extra spaces in the line end, they will create "hard line-break" in that place.

We use a kind of LaTeX renderer for formulas. It looks like this:

$\phi (n) =$ the number of positive integers

less than $n$ that are relatively prime to $n$

where $n >=1$.

The code snippets are created of blocks indented with 4 spaces:

#include <stdio.h>

int main() {

printf("Hello, World\n");

}

For long blocks it would be good to add "show/hide" button. It is created by adding small magic span in the end of

the preceding paragraph <span class="toggle-code">Show/Hide</span>

int phi(int n) {

int result = n;

for(int i = 2; i * i <= n; ++i)

if(n % i == 0) {

while(n % i == 0)

n /= i;

result -= result / i;

}

if(n > 1)

result -= result / n;

return result;

}

###TeX and Markdown references

###Source format

We use [Markdown](https://daringfireball.net/projects/markdown) for source texts and

convert them automatically to HTML.

Some [extra](https://michelf.ca/projects/php-markdown/extra/) features also could be used.

Formulas could be added thanks to `MathJax` library. Simply use `TeX` expressions inside single or double dollar marks `$`, for example:

here is an inline equation: $P \ne NP$

And here is the formula in the separate block:

###Adding images

Small images could be pushed along with texts to the [/img](https://github.com/e-maxx-eng/e-maxx-eng/tree/master/img) subfolder. Let them be in `PNG` format and less than `200kb`. Then you can refer to them inside the article with the tag:


Here `my-image.png` should be your file name, while `&imgroot&` is some magic which will expand to proper url prefix when shown at the site (so you need not know the precise prefix of github raw data).

Larger images should be posted to some image-hosting, like [PostImage](http://postimage.org) or [ImgUr](http://imgur.com/) - they will then give you the url to insert into the page.

You can also embed videos from youtube, as it is done in the `contrib.md` file.