[并行] 并行计算中随机数生成

call random_number(r)

call random_seed(put=seed)

module Random_Mod
  Implicit None
! ran return a uniform random number between 0-1  
! norma return a normal distribution  
contains
  function ran()   !returns random number between 0 - 1  
    implicit none
    integer , save :: flag = 0
    double precision :: ran
    if(flag==0) then
      call random_seed()
      flag = 1
    endif
    call random_number(ran)     ! built in fortran 90 random number function  
  end function ran
  
  function normal(mean,sigma)
    implicit none
    integer :: flag
    double precision, parameter :: pi = 3.141592653589793239  
    double precision :: u1, u2, y1, y2, normal, mean, sigma
    save flag
    data flag /0/
    u1 = ran(); u2 = ran()
    if (flag.eq.0) then
      y1 = sqrt(-2.0d0*log(u1))*cos(2.0d0*pi*u2)
      normal = mean + sigma*y1
      flag = 1
    else
      y2 = sqrt(-2.0d0*log(u1))*sin(2.0d0*pi*u2)
      normal = mean + sigma*y2
      flag = 0
    endif  
  end function normal  
end module Random_Mod
   
   
program main
    use Random_Mod
    use omp_lib
    implicit none
    integer::i
    !real(kind=8)::numit
   
    !$omp parallel private(i)
    !$omp do
    do i = 1,10
        write(*,*)ran()
    end do
    !$omp end do
    !$omp end parallel
end program