"Man pages" for embedded postgresql functions ?

Hi,

I tried to find in the documentation the "advanced" postgresql
functions, as "texticregexeq" (I'm currently trying to build a search
engine for my web sites), but I couldn't find anything seeming to list
all these functions, their behaviour and their use...

They seems to be pretty powerful, and I think that use of these
functions instead of post-queries treatment in PHP (restricting the
display of the result by a loop+condition) would be much more
efficient...
So, haven't I looked in the right place in documentation ?
Could details on these functions be found on www.postgresql.org ?

Thanks for your help, and excuse my "just woken up"-english :)