primecount is a popular C++ library of efficient procedures to
compute prime_pi(x), i.e. π(x),
number of prime numbers <=x, and related functions.
It's an optional package now. The repo is
https://github.com/kimwalisch/primecount
The default Sage implementation of prime_pi is buggy, and a very tricky and old
Cython code - see
https://trac.sagemath.org/ticket/24960
Replacing it with the primecount implementation is the most direct way
to fix it, and it also
gives huge speedups. For this, primecount should be promoted from
optional to standard.
Primecount has a (vendored by default) dependency, a C++ library primesieve,
even more popular.
Many distros have primesieve as a separate package, so we'd like to split
primesieve off primecount, see
https://trac.sagemath.org/ticket/25009
Any objections to this ?
(any objector volunteers to fix Sage's buggy prime_pi :-))
Thanks,
Dima
PS. in the modularization effort, the Cython interface to primecount will become
a separate PyPI package, work in progress on this is on
https://github.com/dimpase/primecountpy
.