!
! File: ~/numerical/random.f90
!
! Program to test f90 intrinsics to generate random numbers,
! (somewhat) randomly seeded off the system clock.
!
! C.G. (12-98)
!
PROGRAM random

  IMPLICIT NONE
  INTEGER :: i, msec, n, time_info(8)
  REAL    :: num(10)
!
! Get all 8 integer fields off the date/time function:
!   time_info(7) = seconds of the minute (range 0 to 60)
!   time_info(8) = milliseconds of the second (range 0 to 999)
!
  CALL DATE_AND_TIME( VALUES = time_info )

  msec = 1000 * time_info(7) + time_info(8)         ! a somewhat random integer

  CALL RANDOM_SEED( SIZE = n )   ! get the number of integers used for the seed

  CALL RANDOM_SEED( PUT = (/ ( i * msec, i = 1, n ) /) )   ! give a proper seed

  CALL RANDOM_NUMBER( num )   ! generate a sequence of 10 pseudo-random numbers

  PRINT '(10F5.2 )', num

END PROGRAM random
!
! Sample output from successive runs:
!
!   0.34 0.79 0.70 0.80 0.50 0.80 0.50 0.21 0.90 0.67
!   0.82 0.22 0.25 0.03 0.34 0.34 0.26 0.07 0.29 1.00
!   0.45 0.83 0.71 0.77 0.17 0.43 0.32 0.90 0.27 0.24
!
! Note: If you don't re-seed (and just directly call 'RANDOM_NUMBER()',
!       then you get the same sequence every time (which may or may not
!       be a problem ... depending on what you're doing)
!