program randt
c
c -- program to test the random number generator
c -- figure 2.7
c
      integer out, length, i, j
      real x(100), mean, std
c
      out = 6
      max = 100
      length = 48
      write(out, 101)
      dummy = rand(1.0)
      do 20 i = 1, 17
       do 10 j = 1, length
        x(j) = rand(0.0)
10     continue
       call meanst(x, length, mean, std)
       write(out, 102) mean, std
20    continue
      write(out, 103)
      stop
101   format('1 test of random number generator'/
     *  '      mean      std dev'/
     *  '      (0.5)     (0.2887)'/
     *  '      ==================')
102   format(1x, 2f10.4)
103   format(/)
      end
      subroutine meanst(x, length, mean, std)
c
c -- find the mean and standard deviation
c
      integer length, i
      real x(1), mean, std, sum, sumsq, xi
c
      sum = 0.0
      sumsq = 0.0
      do 10 i = 1, length
       xi = x(i)
       sum = sum + xi
       sumsq = sumsq + xi*xi
10    continue
      mean = sum / length
      std = sqrt((sumsq - sum*sum/length)/(length -1))
      return
      end