Question

Hi folks, absolute beginner here trying out problem set 1. I've got the code for obtaining the basic information, and the code for the 4 relevant equations, but I can't figure out how to write the code to get the balance after month 1 to become the starting balance for month 2, etc.... can anybody help me with this?

Answer 1

Probably, without seeing any code, just assign the balance after month 1 to whatever variable was the starting balance for month 1 and let it run.

Answer 2

use a loop, modify the balance variable in the loop, on the next iteration (month) it will be the balance for the next month

Answer 3

Thanks for the replies! I thought I tried to create a loop with the following code, but it just gives me the same values I get for Month 1 for months2-12. Any clue where I go wrong?
Code:
#Gets initial values for credit variables from user input
bal = float(raw_input('Enter the outstanding balance on your credit card: '))
apr = float(raw_input('Enter the annual interest rate as a decimal: '))
mpr = float(raw_input('Enter the minimum monthly payment rate as a decimal: '))

#Basic equations that use input values to return the new balance
minpay = mpr*bal
intpaid = apr/12 *bal
prinpaid = minpay - intpaid
newbalance = bal - prinpaid

m = 1
for m in range(1,13):
print 'Month: ', m
print 'Minimum monthly payment: ', minpay
print 'Principle paid: ', prinpaid
print 'Remaining balance: ', newbalance

bal = newbalance

Answer 4

That last bit should read, bal = newbalance, flush under the last print command...

Answer 5

please use a code pasting site:

- http://dpaste.com
- http://pastebin.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 6

Oh ok, sorry about that!

Answer 7

in your loop, what kind of statements are you executing? Are there any statements in the loop that modify bal or newbalance?

Answer 8

when you think about this problem, what happens over and over again each month?

Answer 9

all of the equations are calculated each month (save for 2), because they all involve a quantity that is changing from month to month--the balance. But I thought that if I wrote bal = newbalance, the next time it runs the loop for month two, it should give me the write result, since the bal for month 2 will now be factored into the variables I ask it to output, if that makes sense.

Answer 10

... i don't see any calculations in the for loop, just print statements

Answer 11

Ok, so if put the calculations in the loop and THEN put bal=newbalance, that will solve my problem?

Answer 12

Thanks for taking the time to reply, btw...

Answer 13

the calcs need to be in the loop. does mpr change every month or is it constant?

"... THEN put bal=newbalance, ... " you could just use bal = bal - prinpaid

Answer 14

mpr is constant... yeah, since i just started this stuff yesterday, i keep wanting to create a new variable every time that variable changes... i forget that bal = bal - prinpaid is a possibility

Answer 15

Thanks so much for your help... i think I can get it to work with the info you gave me!

Answer 16

Yay! it worked...

Answer 17

If you're still here, how do I get python to show the return values with two and only decimal places (it's a float return)?

Answer 18

http://docs.python.org/2.7/library/functions.html#round