Siobhan Wojcik wrote:
> Hello,
>
> I've been having an issue with a program that I'm writing. The program
> works until it has to compute something:
>
> def carPmt():
> cost = requestInteger("How much does the car cost?")
> downPmt = requestInteger("If there is a down payment, how much?")
> tradeIn = requestInteger("If there is a trade-in, what is its value?")
> years = requestInteger("How many years will you be paying?")
> air = requestInteger("What is the interest rate?")
>
> payment = calculatePayment(cost,downPmt,tradeIn,years,air)
> print "With a down payment of",downPmt," a trade-in value of",tradeIn,
> print ", an annual interest rate of",air,", your new",cost, "car will
> cost",
> print "you only",payment, "per month."
>
> def calculatePayment(cost,downPmt,tradeIn,years,air):
> carCostInitial = cost - downPmt
> carCostIntermediate = carCostInitial - tradeIn
> monIntRate = air/12
> compoundingFactor = (1.0+monIntRate)**12.0/(1+monIntRate**12.0)-1.0
> monthPmt = monIntRate*carCostIntermediate*compoundingFactor
> return monthPmt
>
>
>
> The first two sections work; the third one does not. When inputting random
> values, I get this: "With a down payment of 5000 ,a trade-in value of 7000
> ,an annual interest rate of 2 ,your new 25000 car will cost you only 0.0
> per month" Obviously I don't want my answer to be 0.0. I've had other
> people look at it (although they aren't well-versed in Python) and they
> couldn't help me isolate the problem.
>
> Thanks a million.
Hint:
>>> 2/12
0
Potential fixes:
>>> 2/12.0
0.16666666666666666
>>> float(2)/12
0.16666666666666666
Or if you want to change the default behaviour for the whole module:
>>> from __future__ import division # at the beginning of the file
>>> 2/12
0.16666666666666666
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