! Module
module mod_rgen 

  private
  public :: rgen

  interface rgen
     module procedure rgen1d, rgen2d
  end interface

contains

  subroutine rgen1d(x)
    real :: x(:)
    call random_number(x)
  end subroutine rgen1d

  subroutine rgen2d(x)
    real :: x(:,:)
    call random_number(x)
  end subroutine rgen2d

end module mod_rgen

! Main program
program main
  use mod_rgen 
  implicit none

  real, allocatable :: a(:,:), b(:)
  integer :: n

  print*, 'Give N'
  read*, n

  allocate(a(n,n),b(n))

  call rgen(a)  ! Calling rgen1d and rgen2d wont work since-
  call rgen(b)  ! -they have been made private in the module

  print*, 'A  is a 2D matrix with values', a
  print*, 'B  is a 1D matrix with values', b

  deallocate(a,b)

end program main