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Fortran code to compute prime numbers.
!****************************************************
! 素数一覧
! : 入力値以下の素数を全て出力する
!
! date name version
! 2017.04.20 mk-mode.com 1.00 新規作成
!
! Copyright(C) 2017 mk-mode.com All Rights Reserved.
!****************************************************
!
program prime_numbers
implicit none
integer i, j, n
logical is_prime
print *, "自然数を入力してください N:"
read *, n
do i = 2, n
is_prime = .true.
do j = 2, int(sqrt(dble(i)))
if (mod(i,j) == 0) then
is_prime = .false. ! 割り切れるので素数ではない
exit
end if
end do
if (is_prime) print *, i ! もし素数ならば出力
end do
end program
@EdThePro101
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EdThePro101 commented Sep 16, 2020

This is awesome! Thank you!

@taymazalizadeh
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taymazalizadeh commented Feb 22, 2022

What change do we have to make in the code if we want to distinguish prime numbers from the numbers we enter?

program prime number
implicit none
integer::n,s,i
read*,n
s=0
do i=1,(n/2)+1
if (mod(n,i)==0)then
s=s+i
end if
end do
if (s==n)then
print*,"yes"
else
print*,"no"
end if
end program prime number

@komasaru
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komasaru commented Feb 23, 2022

Thanks for your comment.
I'm sorry.
I'm not sure what you want to do with this code.
(Is this the code to determine if it is a prime number?)

@taymazalizadeh
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taymazalizadeh commented Feb 26, 2022

yes

@komasaru
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komasaru commented Feb 27, 2022

If you ask me what you should do,
I'm very sorry, but I can only say that you should refer to this 'prime_numbers.f95' code.

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