When I was tidying up my computer I found an implementation of the sieve of Eratosthenes for finding prime number, when I was learning Fortran 77 through Project Euler. I completely forget the detail of implementation (lack of comment!!!) but I hope at some day I can tidy the code up. I think it is using bit array to store the sieve.
Compile the module:
f77 -c eratosthenes.f
Optionally you can supply the -O3 for optimisation.
Link with the main program:
f77 -o main main.f eratosthenes.o
Execute:
./main
The output:
The size of sieve for number under 2038074744 is 16983957
Sieved numbers of prime number: 100000000
The 1 000th prime number is 7919
The 1 000 000th prime number is 15485863
The 100 000 000th prime number is 2038074743
15485863 is a prime number.
1548586 is NOT a prime number.
It should work with N = 2^31 -1, but it is not, no idea why.