wpylib/math/random/rng_lcg48.py

#
# wpylib.math.random.rng_lcg48 module
# Created: 20130814
# Wirawan Purwanto
#

"""
wpylib.math.random.rng_lcg48 module
Implementation of 48-bit Linear Congruential pseudorandom number generator

This RNG is used only for testing and regression purposes.


"""

from wpylib.math.random import rng_base

class lcg48(rng_base):
  """Linear congruential pseudorandom number generator.
  By default this implements the `rannyu' routine."""
  m = 34522712143931  # 11**13
  # This is "seed 1" in the legacy rannyu seed library.
  L = 127
  n = 11863279
  seed_index = 1
  div_two_48 = 2.0**(-48)
  def __call__(self):
    L_new = (self.m * self.L + self.n) & 0xFFFFFFFFFFFF
    self.L = L_new
    if L_new == 0:
      return self.div_two_48
    else:
      return L_new * self.div_two_48
  def update_seed(self, Ln):
    if len(Ln) == 2:
      (self.L, self.n) = (Ln[0], Ln[1])
      self.seed_index = None
    elif len(Ln) == 3:
      (self.seed_index, self.L, self.n) = (Ln[0], Ln[1], Ln[2])
    else:
      raise TypeError, "Unsupported seed type."
  def use_seed_lib(self, index):
    self.m = 34522712143931  # 11**13
    self.update_seed(rannyu_seed_lib[index])

def mkint48(N):
  """Generates a 48-bit number from four integers.
  Used for encoding conversion for legacy rannyu library."""
  return N[3] + (N[2] << 12) + (N[1] << 24) + (N[0] << 36)

def split48(value):
  i4 = value & 0xFFF
  value >>= 12
  i3 = value & 0xFFF
  value >>= 12
  i2 = value & 0xFFF
  value >>= 12
  i1 = value & 0xFFF
  return (i1,i2,i3,i4)


rannyu_seed_lib = [
  (), # 0 is not used
  (1, 127, 11863279),
  (2, 127, 11863259),
  (3, 127, 11863253),
  (4, 127, 11863249),
  (5, 127, 11863237),
  (6, 127, 11863213),
  (7, 152656382984915, 11863279),
  (8, 152656382984915, 11863259),
  (9, 152656382984915, 11863253),
  (10, 152656382984915, 11863249),
  (11, 152656382984915, 11863237),
  (12, 152656382984915, 11863213),
  (13, 127, 11863207),
  (14, 127, 11863183),
  (15, 152656382984915, 11863207),
  (16, 152656382984915, 11863183),
  (17, 152656382984915, 11863171),
  (18, 152656382984915, 11863153),
  (19, 152656382984915, 11863151),
  (20, 152656382984915, 11863133),
  (21, 152656382984915, 11863123),
  (22, 152656382984915, 11863121),
  (23, 152656382984915, 11863109),
  (24, 152656382984915, 11863099),
  (25, 127, 11863171),
  (26, 127, 11863153),
  (27, 127, 11863151),
  (28, 127, 11863133),
  (29, 127, 11863123),
  (30, 127, 11863121),
  (31, 127, 11863109),
  (32, 127, 11863099),
  (33, 152656382984915, 11863073),
  (34, 127, 11863073),
  (35, 152656382984915, 11863067),
  (36, 127, 11863067),
  (37, 152656382984915, 11863057),
  (38, 127, 11863057),
  (39, 152656382984915, 11863039),
  (40, 127, 11863039),
  (41, 152656382984915, 11863037),
  (42, 127, 11863037),
  (43, 127, 11863031),
  (44, 127, 11863021),
  (45, 127, 11862997),
  (46, 127, 11862989),
  (47, 127, 11862979),
  (48, 127, 11862959),
  (49, 127, 11862919),
  (50, 127, 11862911),
  (51, 127, 11862881),
  (52, 127, 11862869),
  (53, 127, 11862857),
  (54, 127, 11862841),
  (55, 127, 11862839),
  (56, 127, 11862803),
  (57, 127, 11862791),
  (58, 127, 11862761),
  (59, 127, 11862713),
  (60, 127, 11862013),
  (61, 127, 11862007),
  (62, 127, 11861987),
  (63, 127, 11861959),
  (64, 127, 11861953),
  (65, 127, 11861923),
  (66, 127, 11861819),
  (67, 127, 11861803),
  (68, 127, 11861791),
  (69, 127, 11861749),
  (70, 127, 11861713),
  (71, 127, 11861711),
  (72, 127, 11861701),
  (73, 152656382984915, 11863031),
  (74, 152656382984915, 11863021),
  (75, 152656382984915, 11862997),
  (76, 152656382984915, 11862989),
  (77, 152656382984915, 11862979),
  (78, 152656382984915, 11862959),
  (79, 152656382984915, 11862919),
  (80, 152656382984915, 11862911),
  (81, 152656382984915, 11862881),
  (82, 152656382984915, 11862869),
  (83, 152656382984915, 11862857),
  (84, 152656382984915, 11862841),
  (85, 152656382984915, 11862839),
  (86, 152656382984915, 11862803),
  (87, 152656382984915, 11862791),
  (88, 152656382984915, 11862761),
  (89, 152656382984915, 11862713),
  (90, 152656382984915, 11862013),
  (91, 152656382984915, 11862007),
  (92, 152656382984915, 11861987),
  (93, 152656382984915, 11861959),
  (94, 152656382984915, 11861953),
  (95, 152656382984915, 11861923),
  (96, 152656382984915, 11861819),
  (97, 152656382984915, 11861803),
  (98, 152656382984915, 11861791),
  (99, 152656382984915, 11861749),
  (100, 152656382984915, 11861713),
  (101, 152656382984915, 11861711),
  (102, 152656382984915, 11861701),
]