text: 
  import numpy as  np
  finfo32 = np.finfo(np.float32)
  finfo64 = np.finfo(np.float64)
  print finfo32
  print finfo64
  # finfo32.resolution = 1e-6
  # finfo64.resolution = 1e-15
  
  # Now that you know how many decimals you want, 
  # say, 15, just use a rstrip("0") to get rid of the unnecessary 0s:
  import random
  with open('reals_1B_15f.data', 'w') as f:
      count = 0
      size = 1000000000
      while count < size:
          value = random.random()
          r = random.randint(0,1)
          if r==0:
              value = -1 * value
          s = ("%.15f\n" % value).rstrip("0")
          f.write(s)
          count +=1
  