mindspore.experimental.optim.Adamax
- class mindspore.experimental.optim.Adamax(params, lr=0.002, betas=(0.9, 0.999), eps=1e-08, weight_decay=0.0, *, maximize=False)[source]
Implements Adamax algorithm (a variant of Adam based on infinity norm).
\[\begin{split}\begin{aligned} &\rule{110mm}{0.4pt} \\ &\textbf{input} : \gamma \text{ (lr)}, \beta_1, \beta_2 \text{ (betas)},\theta_0 \text{ (params)},f(\theta) \text{ (objective)}, \: \lambda \text{ (weight decay)}, \\ &\hspace{13mm} \epsilon \text{ (epsilon)} \\ &\textbf{initialize} : m_0 \leftarrow 0 \text{ ( first moment)}, u_0 \leftarrow 0 \text{ ( infinity norm)} \\[-1.ex] &\rule{110mm}{0.4pt} \\ &\textbf{for} \: t=1 \: \textbf{to} \: \ldots \: \textbf{do} \\ &\hspace{5mm}g_t \leftarrow \nabla_{\theta} f_t (\theta_{t-1}) \\ &\hspace{5mm}if \: \lambda \neq 0 \\ &\hspace{10mm} g_t \leftarrow g_t + \lambda \theta_{t-1} \\ &\hspace{5mm}m_t \leftarrow \beta_1 m_{t-1} + (1 - \beta_1) g_t \\ &\hspace{5mm}u_t \leftarrow \mathrm{max}(\beta_2 u_{t-1}, |g_{t}|+\epsilon) \\ &\hspace{5mm}\theta_t \leftarrow \theta_{t-1} - \frac{\gamma m_t}{(1-\beta^t_1) u_t} \\ &\rule{110mm}{0.4pt} \\[-1.ex] &\bf{return} \: \theta_t \\[-1.ex] &\rule{110mm}{0.4pt} \\[-1.ex] \end{aligned}\end{split}\]Warning
This is an experimental optimizer API that is subject to change. This module must be used with lr scheduler module in LRScheduler Class .
- Parameters
params (Union[list(Parameter), list(dict)]) – list of parameters to optimize or dicts defining parameter groups.
lr (Union[int, float, Tensor], optional) – learning rate. Default:
2e-3
.betas (Tuple[float, float], optional) – coefficients used for computing running averages of gradient and its square. Default:
(0.9, 0.999)
.eps (float, optional) – term added to the denominator to improve numerical stability. Default:
1e-8
.weight_decay (float, optional) – weight decay (L2 penalty). Default:
0.
.
- Keyword Arguments
maximize (bool, optional) – maximize the params based on the objective, instead of minimizing. Default:
False
.
- Inputs:
gradients (tuple[Tensor]) - The gradients of params.
- Raises
ValueError – If the learning rate is not int, float or Tensor.
ValueError – If the learning rate is less than 0.
ValueError – If the eps is less than 0.0.
ValueError – If the weight_decay is less than 0.
ValueError – If elements of the betas not in the range of [0,1).
- Supported Platforms:
Ascend
GPU
CPU
Examples
>>> import mindspore >>> from mindspore import nn >>> from mindspore.experimental import optim >>> # Define the network structure of LeNet5. Refer to >>> # https://gitee.com/mindspore/docs/blob/master/docs/mindspore/code/lenet.py >>> net = LeNet5() >>> loss_fn = nn.SoftmaxCrossEntropyWithLogits(sparse=True) >>> optimizer = optim.Adamax(net.trainable_params(), lr=0.1) >>> def forward_fn(data, label): ... logits = net(data) ... loss = loss_fn(logits, label) ... return loss, logits >>> grad_fn = mindspore.value_and_grad(forward_fn, None, optimizer.parameters, has_aux=True) >>> def train_step(data, label): ... (loss, _), grads = grad_fn(data, label) ... optimizer(grads) ... return loss