squlearn.qnn.loss.LossBase

class squlearn.qnn.loss.LossBase

Base class implementation for loss functions.

abstract gradient(value_dict: dict, **kwargs) → ndarray | tuple[ndarray, ndarray]

Calculates and returns the gradient of the loss.

set_opt_param_op(opt_param_op: bool = True)

Sets the opt_param_op flag.

Parameters:

opt_param_op (bool) – True, if operator has trainable parameters

abstract value(value_dict: dict, **kwargs) → float

Calculates and returns the loss value.

variance(value_dict: dict, **kwargs) → float

Calculates and returns the variance of the loss value.