on_function_eval

BaseCallback.on_function_eval(project, eval_num: int, params: ndarray, fom_value: float, gradient: ndarray | None = None, **kwargs) → None

Called after each objective function evaluation.

This is called every time the objective function is evaluated, which can be multiple times per iteration for optimizers that perform line searches.

Parameters:

projectProject

The optimization project containing parametrization, FOM, etc.

eval_numint

Function evaluation number (1-indexed).

paramsnp.ndarray

Parameter values for this evaluation.

fom_valuefloat

Figure of merit value achieved.

gradientnp.ndarray, optional

Gradient vector (None for gradient-free optimization).

**kwargs

Additional evaluation-specific information (e.g., elapsed_time, is_best).