hw3.py

from math import *
from decimal import *

S=20
lo=Decimal(5)
lh=Decimal(2)
u=Decimal(1)
def p0(y):
    sum1=Decimal(0)
    for i in range(0,y):
        i=Decimal(i)
        sum1+=((lo+lh)**i)/(factorial(i) * u**i)

    sum2=Decimal(0)
    for i in range(y+1,20):
        sum2+=((lo+lh)**y * lh**(i-y))/(factorial(i) * u**i)

    return Decimal(1)/(sum1+sum2)

def p(i,y):
    i=Decimal(i)
    if 0<=i and i<=y:
        return (((lo+lh)**i)/(factorial(i) * u**i)) * p0(y)
    elif i>y and i<=20:
        return (((lo+lh)**y * lh**(i-y))/(factorial(i) * u**i)) * p0(y)

def bo(y):
    sum1=Decimal(0)
    for i in range(y,20):
        sum1+=p(i,y)

    return sum1

for x in range(0,20):
    y=20-x
    BO=bo(y)
    BH=p(20,y)
    print x,y,BO,BH
    print "=========="