Hello

Below is a working code for the sieve .. it has the wheel 23 optimization i.,e all multiples of 2 and 3 are directly ignored (not stored at all). It generates primes upto 10^8 in around ~ 1.6s

Can any 1 suggest a few more optimizations ?

Can the bits(bit,bit1,bit2 in code) be toggled any faster ?

Thank you

Code:#include <ctime> #include <cmath> #include <cstdio> #include <algorithm> #define MAX 100000000 using namespace std; bool isprime[MAX/3]; void make_primes2() { int i,j,lim=sqrt(MAX); bool bit1=1,bit2; for(int i=5;i<=lim;i+=bit1?2:4,bit1=!bit1) { if(!isprime[i/3]) { bit2=1; for(int j=i;;) { j+=bit2?i<<2:i<<1; bit2=!bit2; if(j>=MAX)break; isprime[j/3]=1; } } } } int main() { make_primes2(); printf("%lf(s)\n",clock()/1e6); return 0; }