Raise an exception if the specified schedule is invalid for the sampler.


anneal_schedule (list) – An anneal schedule variation is defined by a series of pairs of floating-point numbers identifying points in the schedule at which to change slope. The first element in the pair is time t in microseconds; the second, normalized persistent current s in the range [0,1]. The resulting schedule is the piecewise-linear curve that connects the provided points.

  • ValueError – If the schedule violates any of the conditions listed below.

  • RuntimeError – If the sampler does not accept the anneal_schedule parameter or if it does not have annealing_time_range or max_anneal_schedule_points properties.

As described in D-Wave System Documentation, an anneal schedule must satisfy the following conditions:

  • Time t must increase for all points in the schedule.

  • For forward annealing, the first point must be (0,0) and the anneal fraction s must increase monotonically.

  • For reverse annealing, the anneal fraction s must start and end at s=1.

  • In the final point, anneal fraction s must equal 1 and time t must not exceed the maximum value in the annealing_time_range property.

  • The number of points must be >=2.

  • The upper bound is system-dependent; check the max_anneal_schedule_points property. For reverse annealing, the maximum number of points allowed is one more than the number given by this property.


This example sets a quench schedule on a D-Wave system.

>>> from dwave.system import DWaveSampler
>>> sampler = DWaveSampler()
>>> quench_schedule=[[0.0, 0.0], [12.0, 0.6], [12.8, 1.0]]
>>> DWaveSampler().validate_anneal_schedule(quench_schedule)