Merge pull request #11532 from jacquesqiao/add-none-layers-api-doc

Add none layers api doc

python/paddle/fluid/clip.py

@@ -24,8 +24,6 @@ __all__ = [
     'GradientClipByValue',
     'GradientClipByNorm',
     'GradientClipByGlobalNorm',
-    'append_gradient_clip_ops',
-    'error_clip_callback',
 ]
 
 
@@ -38,6 +36,25 @@ class BaseErrorClipAttr(object):
 
 
 class ErrorClipByValue(BaseErrorClipAttr):
+    """
+    Clips tensor values to the range [min, max].
+
+    Given a tensor t, this operation clips its value to min and max inplace.
+
+    - Any values less than min are set to min.
+    - Any values greater than max are set to max.
+
+    Args:
+        max (float): The maximum value to clip by.
+        min (float, optional): The minimum value to clip by. if not set by user, \
+        will be set to -max by framework.
+
+    Examples:
+        .. code-block:: python
+
+            var = fluid.framework.Variable(..., error_clip=ErrorClipByValue(max=5.0), ...)
+    """
+
     def __init__(self, max, min=None):
         max = float(max)
         if min is None:
@@ -99,6 +116,31 @@ class NullGradientClipAttr(BaseGradientClipAttr):
 
 
 class GradientClipByValue(BaseGradientClipAttr):
+    """
+    Clips gradient values to the range [min, max].
+
+    Given a tensor t, this operation clips its value to min and max inplace.
+
+    - Any values less than min are set to min.
+    - Any values greater than max are set to max.
+
+    Args:
+        max (float): The maximum value to clip by.
+        min (float, optional): The minimum value to clip by. if not set by user, \
+        will be set to -max by framework.
+
+    Examples:
+        .. code-block:: python
+
+            w_param_attrs = ParamAttr(name=None,
+              initializer=UniformInitializer(low=-1.0, high=1.0, seed=0),
+              learning_rate=1.0,
+              regularizer=L1Decay(1.0),
+              trainable=True,
+              clip=GradientClipByValue(-1.0, 1.0))
+            y_predict = fluid.layers.fc(input=x, size=1, param_attr=w_param_attrs)
+    """
+
     def __init__(self, max, min=None):
         max = float(max)
         if min is None:
@@ -120,6 +162,37 @@ class GradientClipByValue(BaseGradientClipAttr):
 
 
 class GradientClipByNorm(BaseGradientClipAttr):
+    """
+    Clips tensor values to a maximum L2-norm.
+
+    This operator limits the L2 norm of the input :math:`X` within :math:`max\_norm`.
+    If the L2 norm of :math:`X` is less than or equal to :math:`max\_norm`, :math:`Out`
+    will be the same as :math:`X`. If the L2 norm of :math:`X` is greater than
+    :math:`max\_norm`, :math:`X` will be linearly scaled to make the L2 norm of
+    :math:`Out` equal to :math:`max\_norm`, as shown in the following formula:
+
+    .. math::
+
+        Out = \\frac{max\_norm * X}{norm(X)},
+
+    where :math:`norm(X)` represents the L2 norm of :math:`X`.
+
+    Args:
+        clip_norm (float): The maximum norm value
+
+    Examples:
+        .. code-block:: python
+
+            w_param_attrs = ParamAttr(name=None,
+              initializer=UniformInitializer(low=-1.0, high=1.0, seed=0),
+              learning_rate=1.0,
+              regularizer=L1Decay(1.0),
+              trainable=True,
+              clip=GradientClipByNorm(clip_norm=2.0))
+            y_predict = fluid.layers.fc(input=x, size=1, param_attr=w_param_attrs)
+
+    """
+
     def __init__(self, clip_norm):
         self.clip_norm = clip_norm
 
@@ -135,6 +208,44 @@ class GradientClipByNorm(BaseGradientClipAttr):
 
 
 class GradientClipByGlobalNorm(BaseGradientClipAttr):
+    """
+    Clips values of multiple tensors by the ratio of the sum of their norms.
+
+    Given a list of tensors t_list, and a clipping ratio clip_norm, this
+    operation returns a list of clipped tensors list_clipped and the global
+    norm (global_norm) of all tensors in t_list.
+
+    To perform the clipping, the values :math:`t\_list[i]` are set to:
+
+    .. math::
+
+        t\_list[i] = t\_list[i] * \\frac{clip\_norm}{\max(global\_norm, clip\_norm)}
+
+    where:
+
+    .. math::
+
+        global\_norm = \sqrt{\sum_{i=0}^{N-1}(l2norm(t\_list[i]))^2}
+
+    If :math:`clip\_norm > global\_norm` then the entries in t_list remain as they are,
+    otherwise they're all shrunk by the global ratio.
+
+    Args:
+        clip_norm (float): The maximum norm value
+        group_name (str, optional): The group name for this clip.
+
+    Examples:
+        .. code-block:: python
+
+            p_g_clip = fluid.backward.append_backward(loss=avg_cost_clip)
+
+            with fluid.program_guard(main_program=prog_clip):
+                fluid.clip.set_gradient_clip(
+                    fluid.clip.GradientClipByGlobalNorm(clip_norm=2.0))
+                p_g_clip = fluid.clip.append_gradient_clip_ops(p_g_clip)
+
+    """
+
     def __init__(self, clip_norm, group_name="default_group"):
         if not isinstance(group_name, basestring):
             raise TypeError("'group_name' must be a basestring.")
@@ -184,13 +295,14 @@ class GradientClipByGlobalNorm(BaseGradientClipAttr):
 def set_gradient_clip(clip, param_list=None, program=None):
     """
     To specify parameters that require gradient clip.
+
     Args:
         clip(BaseGradientClipAttr): An instance of some derived class of BaseGradientClipAttr,
                 which describes the type and detailed attributes of required gradient clip.
-            param_list(list, None by default): Parameters that require gradient clip. 
+        param_list(list(Variable)): Parameters that require gradient clip.
                 It can be a list of parameter or a list of parameter's name.
                 When it's None, all parameters in the program will be included.
-            program(Program, None by default): The program where parameters are. 
+        program(Program): The program where parameters are.
                 Will be the default main program when assigned with None.
     """
     if not isinstance(clip, BaseGradientClipAttr):

python/paddle/fluid/inferencer.py

@@ -27,13 +27,30 @@ __all__ = ['Inferencer', ]
 
 
 class Inferencer(object):
-    def __init__(self, infer_func, param_path, place=None, parallel=False):
     """
-        :param infer_func: a function that will return predict Variable
-        :param param_path: the path where the inference model is saved by fluid.io.save_params
-        :param place: place to do the inference
-        :param parallel: use parallel_executor to run the inference, it will use multi CPU/GPU.
+    Inferencer High Level API.
+
+    Args:
+        infer_func (Python func): Infer function that will return predict Variable
+        param_path (str): The path where the inference model is saved by fluid.io.save_params
+        place (Place): place to do the inference
+        parallel (bool): use parallel_executor to run the inference, it will use multi CPU/GPU.
+
+    Examples:
+        .. code-block:: python
+
+            def inference_program():
+                x = fluid.layers.data(name='x', shape=[13], dtype='float32')
+                y_predict = fluid.layers.fc(input=x, size=1, act=None)
+                return y_predict
+
+            place = fluid.CPUPlace()
+            inferencer = fluid.Inferencer(
+                infer_func=inference_program, param_path="/tmp/model", place=place)
+
     """
+
+    def __init__(self, infer_func, param_path, place=None, parallel=False):
         self.param_path = param_path
         self.scope = core.Scope()
         self.parallel = parallel
@@ -60,9 +77,20 @@ class Inferencer(object):
 
     def infer(self, inputs, return_numpy=True):
         """
-        :param inputs: a map of {"input_name": input_var} that will be feed into the inference program
-        to get the predict value
-        :return: the predict value of the inference model
+        Do Inference for Inputs
+
+        Args:
+            inputs (map): a map of {"input_name": input_var} that will be feed into the inference program
+            return_numpy (bool): transform return value into numpy or not
+
+        Returns:
+            Tensor or Numpy: the predict value of the inference model for the inputs
+
+        Examples:
+            .. code-block:: python
+
+                tensor_x = numpy.random.uniform(0, 10, [batch_size, 13]).astype("float32")
+                results = inferencer.infer({'x': tensor_x})
         """
         if not isinstance(inputs, dict):
             raise ValueError(

python/paddle/fluid/initializer.py

@@ -19,26 +19,39 @@ from framework import convert_np_dtype_to_dtype_
 from core import VarDesc
 
 __all__ = [
-    'Constant', 'Uniform', 'Normal', 'Xavier', 'Bilinear', 'force_init_on_cpu',
-    'init_on_cpu', 'ConstantInitializer', 'UniformInitializer',
-    'NormalInitializer', 'XavierInitializer', 'BilinearInitializer'
+    'Constant', 'Uniform', 'Normal', 'Xavier', 'Bilinear', 'MSRA',
+    'force_init_on_cpu', 'init_on_cpu', 'ConstantInitializer',
+    'UniformInitializer', 'NormalInitializer', 'XavierInitializer',
+    'BilinearInitializer', 'MSRAInitializer'
 ]
 
 _force_init_on_cpu_ = False
 
 
 def force_init_on_cpu():
+    """
+    The flag of whether force to init variables on CPU.
+
+    Examples:
+        .. code-block:: python
+
+            if force_init_on_cpu():
+                pass
+
+    """
     return _force_init_on_cpu_
 
 
 @contextlib.contextmanager
 def init_on_cpu():
     """
-    Switch program with `with` statement
+    Force the variable to be inited on CPU.
 
     Examples:
-        >>> with init_on_cpu():
-        >>>   step = layers.create_global_var()
+        .. code-block:: python
+
+            with init_on_cpu():
+                step = layers.create_global_var()
 
     """
     global _force_init_on_cpu_
@@ -104,14 +117,18 @@ class Initializer(object):
 
 class ConstantInitializer(Initializer):
     """Implements the constant initializer
-    """
-
-    def __init__(self, value=0.0, force_cpu=False):
-        """Constructor for ConstantInitializer
 
     Args:
-            value: constant value to initialize the variable
+        value (float): constant value to initialize the variable
+
+    Examples:
+        .. code-block:: python
+
+            fc = fluid.layers.fc(input=x, size=10,
+                param_attr=fluid.initializer.Constant(value=2.0))
     """
+
+    def __init__(self, value=0.0, force_cpu=False):
         assert value is not None
         super(ConstantInitializer, self).__init__()
         self._value = value
@@ -146,16 +163,20 @@ class ConstantInitializer(Initializer):
 
 class UniformInitializer(Initializer):
     """Implements the random uniform distribution initializer
-    """
-
-    def __init__(self, low=-1.0, high=1.0, seed=0):
-        """Constructor for UniformInitializer
 
     Args:
-            low: lower boundary of the uniform distribution
-            high: upper boundary of the uniform distribution
-            seed: random seed
+        low (float): lower boundary of the uniform distribution
+        high (float): upper boundary of the uniform distribution
+        seed (int): random seed
+
+    Examples:
+        .. code-block:: python
+
+            fc = fluid.layers.fc(input=x, size=10,
+                param_attr=fluid.initializer.Uniform(low=-0.5, high=0.5))
     """
+
+    def __init__(self, low=-1.0, high=1.0, seed=0):
         assert low is not None
         assert high is not None
         assert high >= low
@@ -196,17 +217,21 @@ class UniformInitializer(Initializer):
 
 
 class NormalInitializer(Initializer):
-    """Implements the  random Normal(Gaussian) distribution initializer
-    """
-
-    def __init__(self, loc=0.0, scale=1.0, seed=0):
-        """Constructor for NormalInitializer
+    """Implements the Random Normal(Gaussian) distribution initializer
 
     Args:
-            loc: mean of the normal distribution
-            scale: standard deviation of the normal distribution
-            seed: random seed
+        loc (float): mean of the normal distribution
+        scale (float): standard deviation of the normal distribution
+        seed (int): random seed
+
+    Examples:
+        .. code-block:: python
+
+            fc = fluid.layers.fc(input=x, size=10,
+                param_attr=fluid.initializer.Normal(loc=0.0, scale=2.0))
     """
+
+    def __init__(self, loc=0.0, scale=1.0, seed=0):
         assert loc is not None
         assert scale is not None
         assert seed is not None
@@ -246,39 +271,49 @@ class NormalInitializer(Initializer):
 
 
 class XavierInitializer(Initializer):
-    """Implements the Xavier initializer
-
+    """
     This class implements the Xavier weight initializer from the paper
-    Understanding the difficulty of training deep feedforward neural
-    networks[1] by Xavier Glorot and Yoshua Bengio.
+    `Understanding the difficulty of training deep feedforward neural
+    networks <http://proceedings.mlr.press/v9/glorot10a/glorot10a.pdf>`_
+    by Xavier Glorot and Yoshua Bengio.
 
     This initializer is designed to keep the scale of the gradients
     approximately same in all the layers. In case of Uniform distribution,
-    the range is [-x, x], where x = sqrt(6 / (fan_in + fan_out)).
+    the range is [-x, x], where
+
+    .. math::
+
+        x = \sqrt{\\frac{6.0}{fan\_in + fan\_out}}
+
     In case of Normal distribution, the mean is 0 and the standard deviation
-    is sqrt(2/ (fan_in + fan_out)).
+    is
 
-    References:
-        [1] Understanding the difficulty of training deep feedforward neural
-            networks. International conference on artificial intelligence and
-            statistics.
-            (http://proceedings.mlr.press/v9/glorot10a.html)
-    """
+    .. math::
+
+        \sqrt{\\frac{2.0}{fan\_in + fan\_out}}
 
-    def __init__(self, uniform=True, fan_in=None, fan_out=None, seed=0):
-        """Constructor for XavierInitializer
 
     Args:
-            uniform: whether to use uniform or normal distribution
-            fan_in: fan_in for Xavier initialization. If None, it is
+        uniform (bool): whether to use uniform or normal distribution
+        fan_in (float): fan_in for Xavier initialization. If None, it is
                 inferred from the variable.
-            fan_out: fan_out for Xavier initialization. If None, it is
+        fan_out (float): fan_out for Xavier initialization. If None, it is
                  inferred from the variable.
-            seed: random seed
+        seed (int): random seed
+
+    Note:
+        It is recommended to set fan_in and fan_out to None for most cases.
+
+    Examples:
+        .. code-block:: python
+
+            fc = fluid.layers.fc(
+                input=queries, size=10,
+                param_attr=fluid.initializer.Xavier(uniform=False))
 
-        Note: It is recommended to set fan_in and fan_out to None for
-              most cases.
     """
+
+    def __init__(self, uniform=True, fan_in=None, fan_out=None, seed=0):
         assert uniform is not None
         assert seed is not None
         super(XavierInitializer, self).__init__()
@@ -342,30 +377,42 @@ class MSRAInitializer(Initializer):
     """Implements the MSRA initializer a.k.a. Kaiming Initializer
 
     This class implements the weight initialization from the paper
-    Delving Deep into Rectifiers: Surpassing Human-Level Performance on
-    ImageNet Classification[1] by Kaiming He, Xiangyu Zhang, Shaoqing Ren
-    and Jian Sun. This is a robust initialization method that particularly
-    considers the rectifier nonlinearities. In case of Uniform distribution,
-    the range is [-x, x], where x = sqrt(6 / fan_in). In case of Normal
-    distribution, the mean is 0 and the standard deviation
-    is sqrt(2/ fan_in).
-
-    References:
-        [1] Delving Deep into Rectifiers: Surpassing Human-Level Performance
-            on ImageNet Classification
-            (https://arxiv.org/abs/1502.01852)
-    """
+    `Delving Deep into Rectifiers: Surpassing Human-Level Performance on
+    ImageNet Classification <https://arxiv.org/abs/1502.01852>`_
+    by Kaiming He, Xiangyu Zhang, Shaoqing Ren and Jian Sun. This is a
+    robust initialization method that particularly considers the rectifier
+    nonlinearities. In case of Uniform distribution, the range is [-x, x], where
 
-    def __init__(self, uniform=True, fan_in=None, seed=0):
-        """Constructor for MSRAInitializer
+    .. math::
+
+        x = \sqrt{\\frac{6.0}{fan\_in}}
+
+    In case of Normal distribution, the mean is 0 and the standard deviation
+    is
+
+    .. math::
+
+        \sqrt{\\frac{2.0}{fan\_in}}
 
     Args:
-            uniform: whether to use uniform or normal distribution
-            fan_in: fan_in for MSRAInitializer. If None, it is
+        uniform (bool): whether to use uniform or normal distribution
+        fan_in (float): fan_in for MSRAInitializer. If None, it is\
         inferred from the variable.
-            seed: random seed
+        seed (int): random seed
+
+    Note:
+        It is recommended to set fan_in to None for most cases.
+
+    Examples:
+        .. code-block:: python
+
+            fc = fluid.layers.fc(
+                input=queries, size=10,
+                param_attr=fluid.initializer.MSRA(uniform=False))
+    """
 
-        Note: It is recommended to set fan_in to None for most cases.
+    def __init__(self, uniform=True, fan_in=None, seed=0):
+        """Constructor for MSRAInitializer
         """
         assert uniform is not None
         assert seed is not None
@@ -425,34 +472,37 @@ class MSRAInitializer(Initializer):
 
 
 class BilinearInitializer(Initializer):
-    """Implements the bilinear initializer.
-
+    """
     This initializer can be used in transposed convolution operator to
     act as upsampling. Users can upsample a feature map with shape of
     (B, C, H, W) by any integer factor. The usage is:
 
-    >>>  factor = 2
-    >>>  w_attr = ParamAttr(learning_rate=0., regularizer=L2Decay(0.),
-    >>>                     initializer=Bilinear())
-    >>>  conv_up = fluid.layers.conv2d_transpose(
-    >>>      input,
-    >>>      num_filters=C,
-    >>>      output_size=None,
-    >>>      filter_size=2 * factor - factor % 2,
-    >>>      padding=ceil((factor - 1) / 2.),
-    >>>      stride=factor,
-    >>>      groups=C,
-    >>>      param_attr=w_attr,
-    >>>      bias_attr=False)
-
-
-    Where, `num_filters=C` and `groups=C` means this is channel-wise tranposed
+    Examples:
+
+        .. code-block:: python
+
+            factor = 2
+            w_attr = ParamAttr(learning_rate=0., regularizer=L2Decay(0.),
+                               initializer=Bilinear())
+            conv_up = fluid.layers.conv2d_transpose(
+                input,
+                num_filters=C,
+                output_size=None,
+                filter_size=2 * factor - factor % 2,
+                padding=ceil((factor - 1) / 2.),
+                stride=factor,
+                groups=C,
+                param_attr=w_attr,
+                bias_attr=False)
+
+    Where, `num_filters=C` and `groups=C` means this is channel-wise transposed
     convolution. The filter shape will be (C, 1, K, K) where K is `filer_size`,
     This initializer will set a (K, K) interpolation kernel for every channel
     of the filter identically. The resulting shape of the output feature map
     will be (B, C, factor * H, factor * W). Note that the learning rate and the
     weight decay are set to 0 in order to keep coefficient values of bilinear
     interpolation unchanged during training.
+
     """
 
     def __init__(self):
@@ -469,7 +519,7 @@ class BilinearInitializer(Initializer):
                            be added.
 
         Returns:
-            the initialization op
+            Operator: the initialization op
 
         Raises:
             ValueError: If type of `var` and `block` is not right.

python/paddle/fluid/optimizer.py

@@ -29,7 +29,7 @@ __all__ = [
     'SGD', 'Momentum', 'Adagrad', 'Adam', 'Adamax', 'DecayedAdagrad', 'Ftrl',
     'SGDOptimizer', 'MomentumOptimizer', 'AdagradOptimizer', 'AdamOptimizer',
     'AdamaxOptimizer', 'DecayedAdagradOptimizer', 'RMSPropOptimizer',
-    'FtrlOptimizer', 'Adadelta', 'ModelAverage', 'Optimizer'
+    'FtrlOptimizer', 'Adadelta', 'ModelAverage', 'Optimizer', 'RMSPropOptimizer'
 ]
 
 
@@ -192,15 +192,15 @@ class Optimizer(object):
         """Add optimization operators to update gradients to variables.
 
         Args:
-          loss: the target that this optimization is for.
-          parameters_and_grads: a list of (variable, gradient) pair to update.
+          loss(Variable): the target that this optimization is for.
+          parameters_and_grads(list(tuple(Variable, Variable))):
+          a list of (variable, gradient) pair to update.
 
         Returns:
           return_op_list: a list of operators that will complete one step of
           optimization. This will include parameter update ops, global step
           update ops and any other custom ops required by subclasses to manage
           their internal state.
-          :param startup_program:
         """
         # This is a default implementation of create_optimization_pass that
         # can be shared by most optimizers. This implementation assumes that
@@ -268,7 +268,22 @@ class Optimizer(object):
 
 
 class SGDOptimizer(Optimizer):
-    """ Simple SGD optimizer without any state.
+    """
+    Optimizer of the stochastic gradient descent algorithm.
+
+    .. math::
+
+        param\_out = param - learning\_rate * grad
+
+    Args:
+        learning_rate (float|Variable): the learning rate used to update parameters. \
+        Can be a float value or a Variable with one float value as data element.
+
+    Examples:
+        .. code-block:: python
+
+            sgd_optimizer = fluid.optimizer.SGD(learning_rate=0.2)
+            sgd_optimizer.minimize(cost)
     """
 
     def __init__(self, learning_rate, **kwargs):
@@ -294,7 +309,37 @@ class SGDOptimizer(Optimizer):
 
 
 class MomentumOptimizer(Optimizer):
-    """Simple Momentum optimizer with velocity state
+    """
+
+    Simple Momentum optimizer with velocity state
+
+    This optimizer has a flag for Nestrov Momentum.
+
+    The update equations are as follows:
+
+    .. math::
+
+        & velocity = mu * velocity + gradient
+
+        & if (use\_nesterov):
+
+        &\quad   param = param - gradient * learning\_rate + mu * velocity * learning\_rate
+
+        & else:
+
+        &\quad   param = param - learning\_rate * velocity
+
+    Args:
+        learning_rate (float|Variable): the learning rate used to update parameters. \
+        Can be a float value or a Variable with one float value as data element.
+        momentum (float): momentum factor
+        use_nesterov (bool): enables Nesterov momentum
+
+    Examples:
+        .. code-block:: python
+
+            optimizer = fluid.optimizer.Momentum(learning_rate=0.2, momentum=0.1)
+            optimizer.minimize(cost)
     """
     _velocity_acc_str = "velocity"
 
@@ -338,7 +383,32 @@ class MomentumOptimizer(Optimizer):
 
 
 class AdagradOptimizer(Optimizer):
-    """Simple Adagrad optimizer with moment state
+    """
+    **Adaptive Gradient Algorithm (Adagrad)**
+
+    The update is done as follows:
+
+    .. math::
+
+        moment\_out &= moment + grad * grad
+
+        param\_out &= param - \\frac{learning\_rate * grad}{\sqrt{moment\_out} + \epsilon}
+
+    The original paper(http://www.jmlr.org/papers/volume12/duchi11a/duchi11a.pdf)
+    does not have the epsilon attribute. It is added here in our implementation
+    as also proposed here: http://cs231n.github.io/neural-networks-3/#ada
+    for numerical stability to avoid the division by zero error.
+
+    Args:
+        learning_rate (float|Variable): the learning rate used to update parameters. \
+        Can be a float value or a Variable with one float value as data element.
+        epsilon (float): a small float value for numerical stability.
+
+    Examples:
+        .. code-block:: python
+
+            optimizer = fluid.optimizer.Adagrad(learning_rate=0.2)
+            optimizer.minimize(cost)
     """
     _moment_acc_str = "moment"
 
@@ -379,7 +449,40 @@ class AdagradOptimizer(Optimizer):
 
 
 class AdamOptimizer(Optimizer):
-    """Implements the Adam Optimizer
+    """
+    This implements the Adam optimizer from Section 2 of the Adam
+    paper : https://arxiv.org/abs/1412.6980.
+    Adam is a first-order gradient-based optimization method based on
+    adaptive estimates of lower-order moments.
+
+    Adam updates:
+
+    .. math::
+
+        t & = t + 1
+
+        moment\_1\_out & = {\\beta}_1 * moment\_1 + (1 - {\\beta}_1) * grad
+
+        moment\_2\_out & = {\\beta}_2 * moment\_2 + (1 - {\\beta}_2) * grad * grad
+
+        learning\_rate & = learning\_rate * \\
+                          \\frac{\sqrt{1 - {\\beta}_2^t}}{1 - {\\beta}_1^t}
+
+        param\_out & = param - learning\_rate * \\frac{moment\_1}{\sqrt{moment\_2} + \epsilon}
+
+    Args:
+        learning_rate (float|Variable): the learning rate used to update parameters. \
+        Can be a float value or a Variable with one float value as data element.
+        beta1 (float): The exponential decay rate for the 1st moment estimates.
+        beta2 (float): The exponential decay rate for the 2nd moment estimates.
+        epsilon (float): a small float value for numerical stability.
+
+    Examples:
+        .. code-block:: python
+
+            optimizer = fluid.optimizer.Adam(learning_rate=0.2)
+            optimizer.minimize(cost)
+
     """
     _moment1_acc_str = "moment1"
     _moment2_acc_str = "moment2"
@@ -484,7 +587,42 @@ class AdamOptimizer(Optimizer):
 
 
 class AdamaxOptimizer(Optimizer):
-    """Implements the Adamax Optimizer
+    """
+    We implement the Adamax optimizer from Section 7 of the Adam
+    paper: https://arxiv.org/abs/1412.6980. Adamax is a variant of the
+    Adam algorithm based on the infinity norm.
+
+    Adamax updates:
+
+    .. math::
+
+        t & = t + 1
+
+        moment\_out & = {\\beta}_1 * moment + (1 - {\\beta}_1) * grad
+
+        inf\_norm\_out & = max({\\beta}_2 * inf\_norm + \epsilon, |grad|)
+
+        learning\_rate & = \\frac{learning\_rate}{1 - {\\beta}_1^t}
+
+        param\_out & = param - learning\_rate * \\frac{moment\_out}{inf\_norm\_out}
+
+
+    The original paper does not have an epsilon attribute.
+    However, it is added here for numerical stability to prevent the
+    division by 0 error.
+
+    Args:
+        learning_rate (float|Variable): the learning rate used to update parameters. \
+        Can be a float value or a Variable with one float value as data element.
+        beta1 (float): The exponential decay rate for the 1st moment estimates.
+        beta2 (float): The exponential decay rate for the 2nd moment estimates.
+        epsilon (float): a small float value for numerical stability.
+
+    Examples:
+        .. code-block:: python
+
+            optimizer = fluid.optimizer.Adamax(learning_rate=0.2)
+            optimizer.minimize(cost)
     """
     _moment_acc_str = "moment"
     _inf_norm_acc_str = "inf_norm"
@@ -568,7 +706,34 @@ class AdamaxOptimizer(Optimizer):
 
 
 class DecayedAdagradOptimizer(Optimizer):
-    """Simple Decayed Adagrad optimizer with moment state
+    """
+    **Decayed Adagrad Optimizer**
+
+    The original paper(http://www.jmlr.org/papers/volume12/duchi11a/duchi11a.pdf)
+
+    The update is done as follows:
+
+    .. math::
+
+        moment\_out & = decay * moment + (1 - decay) * grad * grad
+
+        param\_out & = param - \\frac{learning\_rate * grad}{\sqrt{moment\_out} + \epsilon}
+
+    The original paper(http://www.jmlr.org/papers/volume12/duchi11a/duchi11a.pdf)
+    does not have an epsilon attribute. It is added here for numerical
+    stability to avoid the division by zero error.
+
+    Args:
+        learning_rate (float|Variable): the learning rate used to update parameters. \
+        Can be a float value or a Variable with one float value as data element.
+        decay (float): decay rate.
+        epsilon (float): a small float value for numerical stability.
+
+    Examples:
+        .. code-block:: python
+
+            optimizer = fluid.optimizer.DecayedAdagrad(learning_rate=0.2)
+            optimizer.minimize(cost)
     """
     _moment_acc_str = "moment"
 
@@ -614,6 +779,7 @@ class DecayedAdagradOptimizer(Optimizer):
 class AdadeltaOptimizer(Optimizer):
     """
     **Adadelta Optimizer**
+
     Simple Adadelta optimizer with average squared grad state and
     average squared update state.
     The details of adadelta please refer to this
@@ -703,26 +869,26 @@ class RMSPropOptimizer(Optimizer):
 
     ..  math::
 
-        r(w, t) & = \\rho r(w, t-1) + (1 - \\rho)(\\nabla Q_{i}(w))^2 \\\\
+        r(w, t) & = \\rho r(w, t-1) + (1 - \\rho)(\\nabla Q_{i}(w))^2
 
         w & = w - \\frac{\\eta} {\\sqrt{r(w,t) + \\epsilon}} \\nabla Q_{i}(w)
 
     The first equation calculates moving average of the squared gradient for
-    each weight. Then dividing the gradient by :math: `sqrt{v(w,t)}`.
+    each weight. Then dividing the gradient by :math:`sqrt{v(w,t)}`.
 
     In some cases, adding a momentum term :math: `\\beta` is beneficial.
     In our implementation, Nesterov momentum is used:
 
     ..  math::
 
-        r(w, t) & = \\rho r(w, t-1) + (1 - \\rho)(\\nabla Q_{i}(w))^2 \\\\
+        r(w, t) & = \\rho r(w, t-1) + (1 - \\rho)(\\nabla Q_{i}(w))^2
 
         v(w, t) & = \\beta v(w, t-1) + \\frac{\\eta} {\\sqrt{v(w,t) +
             \\epsilon}} \\nabla Q_{i}(w)
 
         w & = w - v(w, t)
 
-    where, :math: `\\rho` is a hyperparameter and typical values are 0.9, 0.95
+    where, :math:`\\rho` is a hyperparameter and typical values are 0.9, 0.95
     and so on. :math: `beta` is the momentum term. :math: `\\epsilon` is a
     smoothing term to avoid division by zero, usually set somewhere in range
     from 1e-4 to 1e-8.
@@ -733,7 +899,7 @@ class RMSPropOptimizer(Optimizer):
         rho(float): rho is :math: `\\rho` in equation, set 0.95 by default.
         epsilon(float): :math: `\\epsilon` in equation is smoothing term to
             avoid division by zero, set 1e-6 by default.
-        momentum(float): :math: `\\beta` in equation is the momentum term,
+        momentum(float): :math:`\\beta` in equation is the momentum term,
             set 0.0 by default.
 
     Raises:
@@ -952,7 +1118,9 @@ class ModelAverage(Optimizer):
         max_average_window: The maximum size of average window.
 
     Examples:
-        ...
+
+      .. code-block:: python
+
         optimizer = fluid.optimizer.Momentum()
         _, params_grads = optimizer.minimize(cost)
         model_average = fluid.optimizer.ModelAverage(params_grads, 0.15,

python/paddle/fluid/regularizer.py

@@ -16,8 +16,8 @@ import framework
 from . import core
 
 __all__ = [
-    'append_regularization_ops', 'WeightDecayRegularizer', 'L1Decay', 'L2Decay',
-    'L1DecayRegularizer', 'L2DecayRegularizer'
+    'append_regularization_ops', 'L1Decay', 'L2Decay', 'L1DecayRegularizer',
+    'L2DecayRegularizer'
 ]
 
 
@@ -36,7 +36,8 @@ def append_regularization_ops(parameters_and_grads, regularization=None):
                         set. It will be applied with regularizer.
 
     Returns:
-        list of (parameters, gradients) pair with the regularized gradient
+        list[(Variable, Variable)]: list of (parameters, gradients) \
+        pair with the regularized gradient
 
     Raises:
         Exception: Unknown regularization type
@@ -100,6 +101,24 @@ class WeightDecayRegularizer(object):
 
 class L2DecayRegularizer(WeightDecayRegularizer):
     """Implements the L2 Weight Decay Regularization
+
+    Small values of L2 can help prevent over fitting the training data.
+
+    .. math::
+
+        L2WeightDecay = reg\_coeff * parameter
+
+    Args:
+        regularization_coeff(float): regularization coeff
+
+    Examples:
+        .. code-block:: python
+
+            optimizer = fluid.optimizer.Adagrad(
+                learning_rate=1e-4,
+                regularization=fluid.regularizer.L2DecayRegularizer(
+                    regularization_coeff=0.1))
+            optimizer.minimize(avg_cost)
     """
 
     def __init__(self, regularization_coeff=0.0):
@@ -154,6 +173,27 @@ class L2DecayRegularizer(WeightDecayRegularizer):
 
 class L1DecayRegularizer(WeightDecayRegularizer):
     """Implements the L1 Weight Decay Regularization
+
+    L1 regularization encourages sparsity.
+
+    .. math::
+
+        L1WeightDecay = reg\_coeff * sign(parameter)
+
+    Args:
+        regularization_coeff(float): regularization coeff
+
+    Examples:
+        .. code-block:: python
+
+            program = fluid.framework.Program()
+            block = program.global_block()
+            mul_x = block.create_parameter(
+                dtype="float32",
+                shape=[5, 10],
+                lod_level=0,
+                name="mul.x",
+                regularizer=fluid.regularizer.L1DecayRegularizer(0.5))
     """
 
     def __init__(self, regularization_coeff=0.0):