Changeset 391 for python/trunk/Doc/library/random.rst

Timestamp:

Mar 19, 2014, 11:31:01 PM (11 years ago)

Author:

dmik

Message:

python: Merge vendor 2.7.6 to trunk.

Location:

python/trunk

Files:

• . (modified) (1 prop)
• Doc/library/random.rst (modified) (8 diffs)

python/trunk/Doc/library/random.rst

@@ -1 @@
-
 :mod:`random` --- Generate pseudo-random numbers
 ================================================
@@ -6 +5 @@
    :synopsis: Generate pseudo-random numbers with various common distributions.
 
+**Source code:** :source:`Lib/random.py`
+
+--------------
 
 This module implements pseudo-random number generators for various
@@ -53 +55 @@
 
 .. versionchanged:: 2.3
-   Substituted MersenneTwister for Wichmann-Hill.
+   MersenneTwister replaced Wichmann-Hill as the default generator.
+
+The :mod:`random` module also provides the :class:`SystemRandom` class which
+uses the system function :func:`os.urandom` to generate random numbers
+from sources provided by the operating system.
+
+.. warning::
+
+   The pseudo-random generators of this module should not be used for
+   security purposes.  Use :func:`os.urandom` or :class:`SystemRandom` if
+   you require a cryptographically secure pseudo-random number generator.
+
 
 Bookkeeping functions:
@@ -70 +83 @@
       formerly, operating system resources were not used.
 
-   If *x* is not ``None`` or an int or long, ``hash(x)`` is used instead. If *x* is
-   an int or long, *x* is used directly.
-
-
 .. function:: getstate()
 
@@ -89 +98 @@
    *state* should have been obtained from a previous call to :func:`getstate`, and
    :func:`setstate` restores the internal state of the generator to what it was at
-   the time :func:`setstate` was called.
+   the time :func:`getstate` was called.
 
    .. versionadded:: 2.1
@@ -123 +132 @@
 
 
-.. function:: randrange([start,] stop[, step])
+.. function:: randrange(stop)
+              randrange(start, stop[, step])
 
    Return a randomly selected element from ``range(start, stop, step)``.  This is
@@ -195 +205 @@
    depending on floating-point rounding in the equation ``a + (b-a) * random()``.
 
+
 .. function:: triangular(low, high, mode)
 
@@ -224 +235 @@
    Gamma distribution.  (*Not* the gamma function!)  Conditions on the
    parameters are ``alpha > 0`` and ``beta > 0``.
+
+   The probability distribution function is::
+
+                 x ** (alpha - 1) * math.exp(-x / beta)
+       pdf(x) =  --------------------------------------
+                   math.gamma(alpha) * beta ** alpha