diff --git a/python/paddle/fluid/optimizer.py b/python/paddle/fluid/optimizer.py index 54fe9356275c313cd18fbb12edc9d35f38bda772..214e0a7645dcc914d6acc111907f06cc054d4b62 100644 --- a/python/paddle/fluid/optimizer.py +++ b/python/paddle/fluid/optimizer.py @@ -28,8 +28,8 @@ from contextlib import contextmanager __all__ = [ 'SGD', 'Momentum', 'Adagrad', 'Adam', 'Adamax', 'DecayedAdagrad', 'SGDOptimizer', 'MomentumOptimizer', 'AdagradOptimizer', 'AdamOptimizer', - 'AdamaxOptimizer', 'DecayedAdagradOptimizer', 'RMSPropOptimizer', - 'Adadelta', 'ModelAverage', 'Optimizer' + 'AdamaxOptimizer', 'DecayedAdagradOptimizer', 'AdadeltaOptimizer', + 'RMSPropOptimizer', 'Adadelta', 'ModelAverage', 'Optimizer' ] @@ -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 = SGDOptimizer(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): + + & param = param - gradient * learning\_rate + mu * velocity * learning\_rate + + & else: + + & 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 = MomentumOptimizer(learning_rate=0.2, momentum=0.1) + optimizer.minimize(cost) """ _velocity_acc_str = "velocity" @@ -614,6 +659,7 @@ 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 @@ -703,7 +749,7 @@ 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) @@ -844,7 +890,9 @@ 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,