Let's start with some of the following logic . Internet is very large , otherwise the website is very small . No wonder , if a website is very difficult to assert themselves and compete with the billions of websites similar to reveal itself to all internet users .
Users can only see a website where he runs a search on Google and the website will top the list of hits . However, when there are hundreds of similar websites on the Internet , which will appear at the top or bottom of the list of hits ? The answer is poured into a formula PageRank algorithm . As we know , PageRank is a patented algorithm that serves to determine which websites are more important or popular . PageRank is one of the main features of the Google search engine , and was created by its founders , Larry Page and Sergey Brin .
For those of you who know , understand , and use the PageRank , can boost their website to the top of the list of hits . However , the screwing will be punished . But how the PageRank and when a website is in the top of the list of hits ?
The workings of the PageRank formula and the formula
There is thought behind PageRank is simple and genius :
1 . For every website there are a certain number of other websites that put a hyperlink to the website in question .
2 . Each website has a PageRank .
3 . Links from website A to website B is counted as one vote from B to A. As in the voting .
4 . Additionally , the PageRank websites give weight B to A. The higher voice PageRank website B , the better .
5 . Other factors , on how many links are on the website B. The fewer the number , the better for PageRank website A.
6 . The sum of all PageRank is equal to the sum of all documents on the Internet . So , PageRank is the weighting of a document on the Internet as a whole were recorded .
PageRank is calculated for every website , not for the entire bid website . Therefore , a particular article on the webserver may get a higher PageRank than the website itself .
As a whole formula PageRank algorithm looks as follows :
PR ( A ) = ( 1 - d ) + d ( PR ( T1 ) / C ( T1 ) + ... + PR ( Tn ) / C ( TN ) )
The following explanation of the above formula : A website PageRank PageRank is a number of websites T1 to Tn , each divided by the number of links on the website in question . In addition , there is a dampening factor , a very important element that will contribute still further
CALCULATION PAGERANK - Four website to contact each other through links . Depending on the number of links that led to a website , it can be of value in certain PageRank ( PR ) .
The principle of PageRank can be clarified . Suppose that the entire web page consists of only four A , B , C , and D. In each instance the initial PageRank value " 1 " . The amount is equal to the number of websites . In the first instance the website B , C , and D each have a link to a website and no other links . If the dampening factor is omitted, the result is the formula :
PR ( A ) = 1/1 + 1/1 + 1/1
A website's PageRank is 3 . A more complicated example ( see page 199 ) : A website has links to website B and C. B only has a link to A. C has a link to the A , B , and D. D only has a link to B. The formula for A will becomes :
PR ( A ) = 1/1 + 1/3
Links of B is 1, while C only one third the number of links 3 . The result is 1.33 .
For B :
PR ( B ) = 1/2 + 1/3 + 1/1
Rounded result is 1.83 .
For C :
PR ( C ) = ½
The result is 0.5 .
For D :
PR ( D ) = 1/3
The result is rounded 0.33 .
Number PageRank websites A, B , C and D should be equal to the number of websites :
1.33 + 1.83 + 0.5 + 0.33 = 3.99
0.1 Disadvantages caused by rounding . In this calculation still none the less . PageRank of each site not included . Once again we take the example of a website B. When adjusted for PageRank calculations obtained from the first step :
PR ( B ) = 1/2 + 1/3 + 1/1
Obtained the following terms :
PR ( B ) = 1.33 / 2 + 0.5 / 3 + 0.33 / 1
The result is rounded is 1.62 . Of course the new calculation of PageRank website PageRank website B to change A , C , and D. The new value back to change the value of D B. Therefore , Google's PageRank is an iterative approach . We take the results of a calculation in a round for the next iteration step . According to Page and Brin , quite 100 rounds of iterations to achieve a PageRank value is approached from the billions of websites that are on the Internet.
Dampening factor : Include users in the calculations
Based on the assumption of Google , the PageRank represents the possibility of a surfer to a website by clicking a link . Because surfers may not clicking endlessly , then entered into the formula dampening factor .
That said, the dampening factor simulates surfers lose interest following the link . Damping is calculated into the number of voting via the link to the website . In the explanation of the algorithm , Sergey Brin and Larry Page requires damping factor of 0.85 . Can be assumed , in reality Google is indeed revolve around the value of 0.85 .
In contrast to the example above , the actual PageRank is set between 0 and 1 as the value of forecasts . From there a small decimal fractions obtained that produces PageRank of a website . A website with a value of 0.01 has a probability of 1 % gets a visit from a concerned user when clicking a link by chance .
However , these are still a puzzle . If PageRank is expressed as a number between 0 and 1 , why the Google toolbar ( http://toolbar.google.com ) value is displayed between 1 and 10 ? The answer , Google converts . How, is not clear . However, many experts argue , the conversion is not linear , but logarithmic. That is , the leap PageRank of 1 to 2 on the toolbar is much easier than the best value from 9 to 10 .