random.f90

!  
!  Written by Leandro Martínez, 2009-2011.
!  Copyright (c) 2009-2018, Leandro Martínez, Jose Mario Martinez,
!  Ernesto G. Birgin.
!  

!
! Function that returns a real random number between 0. and 1.
! 

double precision function rnd() 
  
  call random_number(rnd)

  return 
end function rnd

!
! Subroutine that initializes the random number generator given a seed
!

subroutine init_random_number(iseed)
  integer :: size
  integer :: i, iseed
  integer, allocatable :: seed(:)
  call random_seed(size=size)
  allocate(seed(size))
  do i = 1, size
    seed(i) = i*iseed
  end do
  call random_seed(put=seed)
  deallocate(seed)
  return
end subroutine init_random_number

!
! Subroutine that uses the date to create a random seed
! 

subroutine seed_from_time(seed)

  implicit none
  integer :: seed, value(8)
  character(len=10) :: b(3)
  call date_and_time( b(1), b(2), b(3), value )
  seed = value(1)+value(2)+value(3)+value(4)+value(5)+value(6)+value(7)+value(8)
  seed = seed + value(1)+value(2)+value(3)+value(4)+value(5)/100+value(6)*100+value(7)/10+value(8)*10

end subroutine seed_from_time