提交 7c1e4862 authored 作者: Pascal Lamblin's avatar Pascal Lamblin

Update the tutorial example on random numbers to account for the default_update…

Update the tutorial example on random numbers to account for the default_update mechanism. Update the corresponding test.
上级 539550b7
......@@ -317,9 +317,9 @@ Here's a brief example. The setup code is:
srng = RandomStreams(seed=234)
rv_u = srng.uniform((2,2))
rv_n = srng.normal((2,2))
f = function([], rv_u, updates=[rv_u.update])
g = function([], rv_n) #omitting rv_n.update
nearly_zeros = function([], rv_u + rv_u - 2 * rv_u, updates=[rv_u.update])
f = function([], rv_u)
g = function([], rv_n, no_default_updates=True) #Not updating rv_n.rng
nearly_zeros = function([], rv_u + rv_u - 2 * rv_u)
Here, 'rv_u' represents a random stream of 2x2 matrices of draws from a uniform
distribution. Likewise, 'rv_n' represenents a random stream of 2x2 matrices of
......@@ -327,15 +327,16 @@ draws from a normal distribution. The distributions that are implemented are
defined in :class:`RandomStreams`.
Now let's use these things. If we call f(), we get random uniform numbers.
Since we are updating the internal state of the random number generator (via
the ``updates`` argument), we get different random numbers every time.
The internal state of the random number generator is automatically updated,
so we get different random numbers every time.
>>> f_val0 = f()
>>> f_val1 = f() #different numbers from f_val0
When we omit the updates argument (as in ``g``) to ``function``, then the
random number generator state is not affected by calling the returned function. So for example,
calling ``g`` multiple times will return the same numbers.
When we add the extra argument ``no_default_updates=True`` to
``function`` (as in ``g``), then the random number generator state is
not affected by calling the returned function. So for example, calling
``g`` multiple times will return the same numbers.
>>> g_val0 = g() # different numbers from f_val0 and f_val1
>>> g_val0 = g() # same numbers as g_val0 !!!
......@@ -345,7 +346,7 @@ single function execution. So the ``nearly_zeros`` function is guaranteed to
return approximately 0 (except for rounding error) even though the ``rv_u``
random variable appears three times in the output expression.
>>> nearly_zeros = function([], rv_u + rv_u - 2 * rv_u, updates=[rv_u.update])
>>> nearly_zeros = function([], rv_u + rv_u - 2 * rv_u)
Seedings Streams
----------------
......
......@@ -19,9 +19,9 @@ class T_SharedRandomStreams(unittest.TestCase):
srng = RandomStreams(seed=234)
rv_u = srng.uniform((2,2))
rv_n = srng.normal((2,2))
f = function([], rv_u, updates=[rv_u.update])
g = function([], rv_n) #omitting rv_n.update
nearly_zeros = function([], rv_u + rv_u - 2 * rv_u, updates=[rv_u.update])
f = function([], rv_u)
g = function([], rv_n, no_default_updates=True) #Not updating rv_n.rng
nearly_zeros = function([], rv_u + rv_u - 2 * rv_u)
assert numpy.all(f() != f())
assert numpy.all(g() == g())
......
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