tff.learning.optimizers.build_yogi

Returns a tff.learning.optimizers.Optimizer for Yogi.

tff.learning.optimizers.build_yogi(
    learning_rate: float,
    beta_1: float = 0.9,
    beta_2: float = 0.999,
    epsilon: float = 0.001,
    initial_preconditioner_value=1e-06
) -> tff.learning.optimizers.Optimizer

The Yogi optimizer is based on Adaptive methods for nonconvex optimization

The update rule given learning rate lr, epsilon eps, accumulator acc, preconditioner s, iteration t, weights w and gradients g is:

acc = beta_1 * acc + (1 - beta_1) * g
s = s + (1 - beta_2) * sign(g - s) * (g ** 2)
normalized_lr = lr * sqrt(1 - beta_2**t) / (1 - beta_1**t)
w = w - normalized_lr * acc / (sqrt(s) + eps)

Implementation of Yogi is based on additive updates, as opposed to multiplicative updates (as in Adam). Experiments show better performance across NLP and Vision tasks both in centralized and federated settings.

Typically use 10x the learning rate used for Adam.

Args
`learning_rate`	A positive `float` for learning rate.
`beta_1`	A `float` between `0.0` and `1.0` for the decay used to track the previous gradients.
`beta_2`	A `float` between `0.0` and `1.0` for the decay used to track the magnitude (second moment) of previous gradients.
`epsilon`	A constant trading off adaptivity and noise..
`initial_preconditioner_value`	The starting value for preconditioner. Only positive values are allowed.

tff.learning.optimizers.build_yogi

Args