# OECheckpoint0¶

Attention

This API is currently available in C++ and Python.

class OECheckpoint0


The OECheckpoint0 class is an abstract class which provides a “callback” facility to monitor the progress of an optimization. In addition, the checkpoint class can also be used to control the termination of an optimization. This class is specifically for use with optimizers which do not use gradients.

The OECheckpoint0 class defines the following public methods:
The following classes derive from this class:

## operator()¶

bool operator()(unsigned int iteration, unsigned int nvar, double fval,
const double *var=(double *) 0, unsigned int state=0)


This operator method is called by an optimizer at least once per iteration during an optimization. The variables passed to the method from the optimizer reflect the current state of an optimization.

iteration
The iteration number.
nvar
The number of variables.
fval
The most recent function evaluation during the current iteration.
var
Array containing current set of optimized variables. If available, the array has a length of nvar.
state
The current state of optimization.