Why google not updating Page Rank?

[azevedo]

I have seen changes of page rank in many websites. I don't know how you are saying that Google is not updating page rank. Even according to me Google keep on changing page rank on time to time basis. I am not aware about the exact time limit.

[RichardCarter]

Google has changed it's reaction towards the search query, now PR is not that much important for Google to display queries, I think that's why Google is not updating Page Rank.

[MelWhitmer]

Google has recently changed their reaction towards the search queries so I think they might be now working with this changed reaction to update Page Rank.