[Tutor] HELP!!!!

[Bob Gailer]

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At 06:20 PM 2/8/2003 -0500, you wrote:
>Sure, this is what I have so far:
>n = 1
>amount = input("What is your initial deposit?  ")
>p = input("Please enter your interest rate  ")
>while amount < 1000000:
>       amount = amount(1 + p/100)**n
>       n = n + 1
>print n, "years"
>print amount
>
>this is what I get along with this error message:
>What is your initial deposit?  1000
>Please enter your interest rate  10
>Traceback (most recent call last):
>   File "C:\Python22\million.py", line 5, in ?
>     amount = amount(1 + p/100)**n
>TypeError: 'int' object is not callable

1) in amount = amount(1 + p/100)**n the parentheses after amount look like 
a function call. Amount isn't a function, its an int, so you get the 
TypeError. If you want multiplication, use an *: amount = amount*(1 + p/100)**n

2) assuming that the user enters an integer for interest, p/100 becomes 
integer division resulting in 0; amount will never change.
So try amount = amount*(1 + p/100.0)**n

3) 1 + p/100.0 is a "loop invariant", meaning that the result is the same 
each pass through the loop. In this program it does not matter; as programs 
grow it can help with efficiency to move such calculations outside the loop:
rate = 1 + p/100.0
while ...
   amount = amount*rate**n

Also when replying please include tutor@python.org so everyone can see your 
messages.

Also as has been mentioned, use a meaningful subject line.

Bob Gailer
mailto:ramrom@earthling.net
303 442 2625

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