焼きなまし法(http://d.hatena.ne.jp/jetbead/20120623/1340419446) をpythonへ

yakinamashi.py

# -*- coding: utf-8 -*-
# author: @taki__taki__
# date: 30/06/2015

from random import random
from math import exp

class SA(object):
	# function
	def f(self, x):
		return -3*x*x*x*x + 3*x*x*x + 10*x*x - 10*x + 15.0

	# initializing parameters
	def __init__(self, init_x, t, r):
		self.x = init_x
		self.z = init_x
		self.best = self.f(self.z)
		self.T = t
		self.R = r

	# return answer
	def get_best(self):
		return self.z

	# updating functions
	def get_random_neighbor(self, xx):
		return xx + 0.01 if random() < 0.5 else xx - 0.01

	def next_T(self, t):
		return t * 0.995

	def next_R(self, r):
		return self.R

	# search
	def calc(self):
		while self.T > 1.0:
			for r in xrange(self.R):
				y = self.get_random_neighbor(self.x)
				fx = self.f(self.x)
				delta = fx - self.f(y)

				if delta < 0.0 or exp(-delta / self.T) > random():
					self.x = y

				if fx > self.best:
					self.best = fx
					self.z = self.x

				# output search process
				print( self.x )
			print("#{0}".format(self.best))
			self.T = self.next_T(self.T)
			self.R = self.next_R(self.R)
		return 0

if __name__ == '__main__':
	sa = SA(0.001, 100, 1000)
	sa.calc()
	print( sa.get_best() )