import math


def boltzmann_accept_prob (d_perf, temperature):
    """Boltzmann accepting probability function for the simulated annealing
    evolver.
    
    Parameters
    ----------
    d_perf : float
        Change in performance value in last iteration.

    temperature :  float
        Current temperature of the simulated annealing process.
    """
    return math.exp(d_perf / temperature);