I waned share, and possibly stick in as an example on how to use WITH RECURSIVE, little thing that I wrote just to prove that I can understand how it works.
It calculates PI, algorithm is pretty simple. I'll give you 2 versions. C++ one , and SQL one :D Let me know, what ya think
so here we go.
C++ code:
iterations *= 2;
for (unsigned int i=0; i<iterations; i+=4)-
{
double t1, t2;
t1 = 4.0/(3+i) ;
t2 = 4.0/(3+i+2);
pisub += t1;
piadd += t2 ;
}
double ourPi = 4 + piadd - pisub;
SQL:
WITH RECURSIVE t AS
(
select 0::float8 as subs, 0::float8 as adds, 0 as x
UNION ALL
select (4::float8)/(3+x) as subs, (4::float8)/(3+x+2) as adds, x+4 as x from t where x < 10000
)
select 4::float8 + sum(adds) - sum(subs) from t;
comments are welcomed :)
you obviously need CVS HEAD to run it, and please don't ask how to get it, etc. :)
