diff options
author | Ulrich Bauer <ulrich.bauer@tum.de> | 2016-05-10 22:23:04 +0200 |
---|---|---|
committer | Ulrich Bauer <ulrich.bauer@tum.de> | 2016-05-10 22:23:04 +0200 |
commit | b26818e31c9588290d42c62628cef6a6d07442ac (patch) | |
tree | a024e01852b1945b4a8814ae239d31c66009486f /ripser.cpp | |
parent | 4c9b346216f0c148ea32b980b63630d6140d90a3 (diff) |
primality check
Diffstat (limited to 'ripser.cpp')
-rw-r--r-- | ripser.cpp | 5 |
1 files changed, 3 insertions, 2 deletions
@@ -776,8 +776,9 @@ void compute_pairs( #endif } -bool is_prime(const unsigned long n) { - for (unsigned long i = 2; i*i <= n; ++i) if (n%i == 0) return false; +bool is_prime(const coefficient_t n) { + if (!(n & 1) || n < 2 ) return n == 2; + for (coefficient_t p = 3, q = n/p, r = n%p; p <= q; p += 2, q = n/p, r = n%p) if (!r) return false; return true; } |