performance - A Small Python 2.5.4 Program: Does This Code Do The Desired Job? -

i'm learning python 2.5.4 programming language using mit ocw scholar course 6.00.

i have written program, same input, program's output differs output mit people have shown program produce.

i wish write python 2.5.4 program current outstanding balance , annual interest rate input user, , uses bisection search method find minimum fixed minimum monthly payment cause balance fall below 0 within 12 months. program displays right monthly amount, number of months needed claer outstanding amount, , final balance.

here's code:

# start of code  balance = float(raw_input('enter outstanding balance on credit card: '))  interestrate = float(raw_input('enter annual credit card interest     rate decimal: '))  lower = balance / 12.0  upper = ( balance * ( 1 + interestrate / 12.0 ) ** 12.0 ) / 12.0  payment = ( lower + upper ) / 2.0  currentbalance = balance  while currentbalance > 0:     months in range(1, 13):         currentbalance = currentbalance * ( 1 + interestrate / 12.0 ) - payment         if currentbalance <= 0:             break     if currentbalance <= 0:         break     else:         lower = payment         payment = ( lower + upper ) / 2.0         currentbalance = balance  print 'result' print 'monthly payment pay off debt in 1 year:', '$' +   str(round(payment, 2)) print 'number of months needed:', months print 'balance:', '$' + str(round(currentbalance, 2)) #end of code 

does code desired job? if not, lies problem? and, how fix it? if program right, in ways can improved?

please bear in mind i'm beginner.

regards.

you have couple of typos (which may have been introduced when copying posting):

• you split balance on credit / card: across line-ending, give syntaxerror

• currentbalance = currentbalance * ( 1 + interestrate / 12.0 ) payment missing - operator before payment

the first logical error is

    if currentbalance <= 0:         break 

... stop find higher needed payment; ever increase possible payment values (lower = payment), never decrease (you should have clause leading upper = payment, otherwise bisection search lopsided).

once that, have add new test know when stop looping. target accuracy - payment nearest cent? how know when have found it?

my other suggestion improve code organization defining operations functions - get_float(prompt) , final_balance(current_balance, interest_rate, num_payments) obvious candidates.