## Wednesday, 8 April 2009

### Reveal The PR Secret (III) -PageRank Calculation-

Four website contact each other through links. Depending on the number of links that take to a website, the PageRank values can be in a certain (PR). The principle of PageRank can be explained. Assume only the entire web site consists of four A, B, C, and D. In the example each have a PageRank value of initial "1". The amount is equal to the number of websites. In the first website B, C, and D each have a link to a website and no other links. When the reducer factors are ignored, the result is the formula:

PR (A) = 1 / 1 + 1 / 1 + 1 / 1
A website is PageRank 3. A more complex 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 A, B, and D. D only has a link to B. A formula will be to:

PR (A) = 1 / 1 + 1 / 3
Link B value of 1, while the C of only 1 / 3 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 of PageRank website A, B, C and D should be equal to the number of website:
1.33 + 1.83 + 0.5 + 0.33 = 3.99

Lack of 0.1 is caused by rounding. In this calculation that there is still insufficient. PageRank of each web site is not included. Once again we take the example website B. When adjusted to the PageRank calculation is obtained from the first step:
PR (B) = 1 / 2 + 1 / 3 + 1 / 1

Obtained following terms:
PR (B) = 1.33 / 2 + 0.5 / 3 + 0.33 / 1