Many programming languages allow you to specify computations to be run in parallel.
While Concurrent computing is focused on concurrency,
the purpose of this task is to distribute time-consuming calculations
on as many CPUs as possible.

Assume we have a collection of numbers, and want to find the one
with the largest minimal prime factor
(that is, the one that contains relatively large factors).
To speed up the search, the factorization should be done
in parallel using separate threads or processes,
to take advantage of multi-core CPUs.

Show how this can be formulated in your language.
Parallelize the factorization of those numbers,
then search the returned list of numbers and factors
for the largest minimal factor,
and return that number and its prime factors.

For the prime number decomposition
you may use the solution of the Prime decomposition task.

 
program Primes
 
    use ISO_FORTRAN_ENV
 
    implicit none
 
    integer(int64), dimension(7) :: data = (/2099726827, 15780709, 1122725370, 15808973, 576460741, 12878611, 12757923/)
    integer(int64), dimension(100) :: outprimes
    integer(int64) :: largest_factor = 0, largest = 0, minim = 0, val = 0
    integer(int16) :: count = 0, OMP_GET_THREAD_NUM
 
    call omp_set_num_threads(4);
    !$omp parallel do private(val,outprimes,count) shared(data,largest_factor,largest)
    do val = 1, 7
        outprimes = 0
        call find_factors(data(val), outprimes, count)
        minim = minval(outprimes(1:count))
        if (minim > largest_factor) then
            largest_factor = minim
            largest = data(val)
        end if
        write(*, fmt = '(A7,i0,A2,i12,100i12)') 'Thread ', OMP_GET_THREAD_NUM(), ': ', data(val), outprimes(1:count)
    end do
    !$omp end parallel do
 
    write(*, fmt = '(i0,A26,i0)') largest, ' have the Largest factor: ', largest_factor
 
    return
 
contains
 
    subroutine find_factors(n, d, count)
        integer(int64), intent(in) :: n
        integer(int64), dimension(:), intent(out) :: d
        integer(int16), intent(out) :: count
        integer(int16) :: i
        integer(int64) :: div, next, rest
 
        i = 1
        div = 2; next = 3; rest = n
 
        do while (rest /= 1)
            do while (mod(rest, div) == 0)
                d(i) = div
                i = i + 1
                rest = rest / div
            end do
            div = next
            next = next + 2
        end do
        count = i - 1
    end subroutine find_factors
 
end program Primes
 