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Using bisection search to determine

I have posted other thread but it did not receive answers thus i'm trying to provide some of my work to make more clear.

I need to use bisection method to determine monthly payment in order to pay off debt in one year exactly.

Here's some code:

originalBalance = 320000
annualInterestRate = 0.2
monthly_interest = annualInterestRate / 12
low = originalBalance/12
high = (originalBalance*(1 + monthly_interest)**12)/12
epsilon = 0.01
min_payment = (high + low)/2.0while min_payment*12 - originalBalance >= epsilon:for month in range(0, 12):balance = (originalBalance - min_payment) * (1+monthly_interest)if balance < 0:low = min_paymentelif balance > 0:high = min_paymentmin_payment = (high + low)/2.0
print "lowest payment: " + str(balance)

However, I receive very way off answer: 298222.173851

My friend told me that correct answer is : 29157.09

Which is a lot lower than my...I guess the problem is in rounding(which I did not do yet) and preserving the balance after every looping and resetting it if balance is over 0. I cannot figure out how to attempt this problem and please, help someone :)

This is the correct one.

originalBalance = 320000
annualInterestRate = 0.2
monthly_interest = annualInterestRate / 12
low = originalBalance/12
high = (originalBalance*(1 + monthly_interest)**12)/12
epsilon = 0.01
min_payment = (high + low)/2.0while min_payment*12 - originalBalance >= epsilon:for month in range(0, 12):balance = (originalBalance - min_payment)/10 * (1+monthly_interest)if balance < 0:low = min_paymentelif balance > 0:high = min_paymentmin_payment = (high + low)/2.0
print "lowest payment: " + str(balance)