Box Generator / Sprache Python
 
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Der in SprachePython umgesetzte Pseudocode

import RandomNumberGenerator
import math

class RandBox:
    """ generator for gaussian deviates (Box-Mueller) """

        
    def __init__(self):
        self.__random = \ RandomNumberGenerator.defaultInstance()
        self.__available = 0


    def next(self):
        """ move to the next element of the pseudo random
            sequence """
        # moving to the next element either uses up one 
        # deviate or triggers the generation of two new 
        # deviates
        if self.__available:
            self.__available = 0
        else:
            self.__generate()

    def lastGaussian(self):
        """ pseudo random deviate from the
            gaussian distribution """
        if self.__available:
            return self.__first
        else:
            return self.__second
        

    def __generate(self):
        """ generate two pseudo random deviates from a 
            gaussian distribution """
        self.__randpoint()
        p = math.sqrt(((-2.0 * math.log(self.__product)/\                         self.__product)))
        self.__available = 1
        self.__first = p * self.__x
        self.__second = p * self.__y

    def __randpoint(self):
        """ a point from a uniform distribution on the 
            area of the unit circle """
        self.__product = 2
        while self.__product > 1:
            self.__x = self.__randuniv() * 2.0 - 1.0
            self.__y = self.__randuniv() * 2.0 - 1.0
            self.__product = self.__x * self.__x + \ self.__y * self.__y

    __x = 0.0
    __y = 0.0
    __product = 0.0
    __first = 0.0
    __second = 0.0
    __available = 0
    __random = 0

            
    def __randuniv(self):
        """ internal wrapper for uniform distribution on 
            unit interval """
        self.__random.next()
        return self.__random.lastUniform()


KategorieProgrammierBeispiele KategoriePython
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