Reorganization of all modules.

stegano/lsbset/generators.py

@@ -0,0 +1,156 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Stéganô - Stéganô is a basic Python Steganography module.
+# Copyright (C) 2010-2016  Cédric Bonhomme - https://www.cedricbonhomme.org
+#
+# For more information : https://github.com/cedricbonhomme/Stegano
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>
+
+__author__ = "Cedric Bonhomme"
+__version__ = "$Revision: 0.2 $"
+__date__ = "$Date: 2011/12/28 $"
+__revision__ = "$Date: 2012/12/14 $"
+__license__ = "GPLv3"
+
+import math
+import itertools
+
+def identity():
+    """
+    f(x) = x
+    """
+    n = 0
+    while True:
+        yield n
+        n += 1
+
+def Dead_Man_Walking():
+    n = 0
+    while True:
+        yield n + 7
+        n += 2
+
+def OEIS_A000217():
+    """
+    http://oeis.org/A000217
+    Triangular numbers: a(n) = C(n+1,2) = n(n+1)/2 = 0+1+2+...+n.
+    """
+    n = 0
+    while True:
+        yield (n*(n+1))//2
+        n += 1
+
+def fermat():
+    """
+    Generate the n-th Fermat Number.
+    """
+    y = 5
+    while True:
+        yield y
+        y = pow(y-1,2)+1
+
+def mersenne():
+    """
+    Generate 2^n-1.
+    """
+    y = 1
+    while True:
+        yield y
+        y = 2*y + 1
+
+def eratosthenes():
+    """
+    Generate the prime numbers with the sieve of Eratosthenes.
+    """
+    d = {}
+    for i in itertools.count(2):
+        if i in d:
+            for j in d[i]:
+                d[i + j] = d.get(i + j, []) + [j]
+            del d[i]
+        else:
+            d[i * i] = [i]
+            yield i
+
+def eratosthenes_composite():
+    """
+    Generate the composite numbers with the sieve of Eratosthenes.
+    """
+    p1 = 3
+    for p2 in eratosthenes():
+        for n in range(p1 + 1, p2):
+            yield n
+        p1 = p2
+
+def carmichael():
+    for m in eratosthenes_composite():
+        for a in range(2, m):
+            if pow(a,m,m) != a:
+                break
+        else:
+            yield m
+
+def ackermann(m, n):
+    """
+    Ackermann number.
+    """
+    if m == 0:
+        return n + 1
+    elif n == 0:
+        return ackermann(m - 1, 1)
+    else:
+        return ackermann(m - 1, ackermann(m, n - 1))
+
+def fibonacci():
+    """
+    A generator for Fibonacci numbers, goes to next number in series on each call.
+    This generator start at 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, ...
+    See: http://oeis.org/A000045
+    """
+    a, b = 1, 2
+    while True:
+        yield a
+        a, b = b, a + b
+
+def syracuse(l=15):
+    """
+    Generate the sequence of Syracuse.
+    """
+    y = l
+    while True:
+        yield y
+        q,r = divmod(y,2)
+        if r == 0:
+            y = q
+        else:
+            y = 3*y + 1
+
+def log_gen():
+    """
+    Logarithmic generator.
+    """
+    y = 1
+    while True:
+        adder = max(1, math.pow(10, int(math.log10(y))))
+        yield int(y)
+        y = y + adder
+
+if __name__ == "__main__":
+    # Point of entry in execution mode.
+    f = fibonacci()
+    for x in range(13):
+        #print(next(f), end=' ') # 0 1 1 2 3 5 8 13 21 34 55 89 144
+        pass