DLARUV returns a vector of n random real numbers from a uniform (0,1)
 distribution (n <= 128).

 This is an auxiliary routine called by DLARNV and ZLARNV.

          ISEED is INTEGER array, dimension (4)
          On entry, the seed of the random number generator; the array
          elements must be between 0 and 4095, and ISEED(4) must be
          odd.
          On exit, the seed is updated.

          N is INTEGER
          The number of random numbers to be generated. N <= 128.

          X is DOUBLE PRECISION array, dimension (N)
          The generated random numbers.

  This routine uses a multiplicative congruential method with modulus
  2**48 and multiplier 33952834046453 (see G.S.Fishman,
  'Multiplicative congruential random number generators with modulus
  2**b: an exhaustive analysis for b = 32 and a partial analysis for
  b = 48', Math. Comp. 189, pp 331-344, 1990).

  48-bit integers are stored in 4 integer array elements with 12 bits
  per element. Hence the routine is portable across machines with
  integers of 32 bits or more.