Using Fortran90's intrinsic RANDOM_NUMBER subroutine

There are three steps involved:

1. Allocating the seed
2. Setting the seed using either (a) the system clock, or (b) a user-defined number
3. Harvesting the random numbers

Here is a minimal program which demonstrates the use of Fortran's intrinsic random number generator

	!
	! Program to demonstrate the use of Fortran 90's intrinsic random_number()
	!
	program main
	integer :: values(8), k, nseed
	integer, dimension(:), allocatable :: seed
	real(8) :: r(10)
	!
	! Step 1: To over-ride "default seed", you have to initialize it first
	!
	call random_seed(size = k)
	allocate(seed(1:k))
	!
	! Step 2a: You may use the "milliseconds" from the system clock to set it automatically
	!
	call date_and_time(values=values) ! t
	seed(:) = values(8)
	!
	! Step 2b: Or set it to a value you want (to reproduce errors for example)
	! UNCOMMENT TO USE
	!
	! nseed = 5
	! seed(:) = nseed
	! call random_seed(put = seed)
	!
	! A call to random_number populates the "matrix" "r" in general
	!
	call random_number(r)
	do i = 1, 10
	write(*,'(f7.4)') r(i)
	enddo
	end program main

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