dr.botzo/modules/Pi.py

"""
Pi - calculate pi over time via the monte carlo method. idea borrowed from #linode
Copyright (C) 2010  Brian S. Stephan

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

from ConfigParser import NoOptionError, NoSectionError
import math
import random

from extlib import irclib

from Module import Module

class Pi(Module):
    """
    Use the Monte Carlo method to approximate pi. Each time this method is called,
    it calculates a random point inside a square on the xy plane. If that point also
    falls within a circle bound within that square, it is added to the count of points
    inside. Over time, 4 * count_inside / count approaches pi.

    Idea from #linode on OFTC. Code from http://www.eveandersson.com/pi/monte-carlo-circle
    """

    def do(self, connection, event, nick, userhost, replypath, what, admin_unlocked):
        if what == "pi":
            try:
                if not self.config.has_section(self.__class__.__name__):
                    self.config.add_section(self.__class__.__name__)

                # set default values if unset
                if not self.config.has_option(self.__class__.__name__, "count_inside"):
                    self.config.set(self.__class__.__name__, "count_inside", "0")
                if not self.config.has_option(self.__class__.__name__, "count"):
                    self.config.set(self.__class__.__name__, "count", "0")

                # load values from config
                count_inside    = self.config.getint(self.__class__.__name__, "count_inside")
                count           = self.config.getint(self.__class__.__name__, "count")

                x = random.random()
                y = random.random()
                inside = False
                d = math.hypot(x,y)
                if d < 1:
                    inside = True
                    count_inside += 1
                count += 1
                pi = 4.0 * count_inside / count

                self.config.set(self.__class__.__name__, "count_inside", str(count_inside))
                self.config.set(self.__class__.__name__, "count", str(count))

                return self.reply(connection, replypath, "({0:.10f}, {1:.10f}) is {2}within the circle. pi is {5:.10f} ({3:d}/{4:d}).".format(x, y, "" if inside else "not ", count_inside, count, pi));
            except NoOptionError, NoSectionError: pass

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