Question

Hi everyone!

I'm a bit confused about bisectioning in pset 1, problem 3. I understand how it chooses an upper and lower bound initially, and how it changes one of the two depending on an if statement. What I'm not sure about is what that if statement is in the context of the problem. Something like::
if minmonpay < x
low = minmonpay
else:
high = minmonpay

I can post what I have so far, but openstudy is being finnicky about what it wants to let me copy and paste. Thanks in advance!

Answer 1

outBalance = float(raw_input('Enter the outstanding balance on your credit card: '))
annInt = float(raw_input('Enter the annual credit card interest rate as a decimal: '))

balance = outBalance
low = outBalance/12.0
high = (outBalance * (1 + (annInt/12.0)) ** 12.0)/12.0
minMonPay = (high + low)/2
monthInt = (annInt/12.0)

while balance > 0:
month = 0
balance = outBalance
if monthPay < x
low = minMonPay
else:
high = minMonPay

while balance > 0 and month < 12
month += 1
interest = monthInt + balance
balance -= minMonPay
balance += interest

print 'Result'
print 'Monthly payment to pay off debt in a year: ',round(minMonPay,2)
print 'Number of months needed: ',month
print 'Balance: ',round(balance,2)

here's what I have so far

Answer 2

For pasting, you could use pastebin or dpaste. That way when people copy the code and paste it they can have it work. If I try to copy what you wrote, it collapses down to one line. =/

Answer 3

: missing on the if statement.

Answer 4

And on the inner while loop.

Answer 5

Where did "if monthPay < x" come from? monthPay is not defined.

http://dpaste.com/1296423/

Answer 6

@Avakuum
please use a code pasting site:

- http://dpaste.com
- http://pastebin.com
- https://gist.github.com/
- http://www.repl.it/
- http://pastie.org
- http://codepad.org
- http://ideone.com

paste your code there and post the link here. select Python syntax highlighting when u paste.

Answer 7

somtimes (a lot of times) it helps to right down in words what you are trying to do

you define a searchspace using high and low
you pick the middle item of that space and test it
if it is just right stop and report the answer
if it is too low you define a new search space that is the upper half of the previous space
if it is too high you define a new search space that is the lower half of the previous space
repeat

Answer 8

looks like you might be missing one of the ifs