[Tutor] Is this correct?

[cclpianos at comcast.net]

Hello again, just getting back to the computer, real world etc.

I hate to say this, but I never did well in algebra. But I am  
determined to slog through this to understand it well.
On Feb 8, 2009, at 7:29 PM, bob gailer wrote:

> Please always reply-all so a copy goes to the list. We all  
> participate and learn.
>
> Would you also respond to my requests for clarified algorithm?
>
> cclpianos at comcast.net wrote:
>> Hi Bob,
>> Thanks for your input! I ran the program in IDLE and it worked  
>> just fine. Apparently my calculations were correct, although  
>> sloppy. Some very good points for me to consider;
>
> Thanks for the acknowledgment.
>>
>> Indentation. I felt for myself it was a bit more readable, but  
>> considering I'm new and the formatting may not survive other OS's,  
>> I plan on making those changes.
>
>> The use of the 1.041 for the interest rate. Here, as I'm not  
>> mathematically inclined I don't see the advantages, but I'll  
>> compare the program to yours to see how it works.
>
> Your calculation was, in effect, principal = principal + principal  
> * interest. Do you recall factoring in algebra?
>
> principal = principal * (1 + interest). For me it is a little  
> easier on the eyes and thinking to see the latter.

Yes, this is way easier on the eyes!
>
> You could also do:
>
> principal += principal * interest
>

Thanks for your explanation.

Pat
>
>
>> Starting the count at 2 and eliminating the other if statements is  
>> a great simplification.
>> It all seems a bit clearer in your rendition.
>> Thanks again, Pat
>>
>> On Feb 8, 2009, at 3:11 PM, bob gailer wrote:
>>
>>> principal = balance = 500000 # Starting fund amount.
>>> interestRate = .05 # Interest rate added to the principal annually.
>>> tuition = 34986 # Starting tuition fee
>>> tuitionInc = 1.041 # The annual increase applied to the tuition.
>>> print principal, "Is the starting principal" # This is to show  
>>> the starting balance.
>>> print tuition, "Is the starting tuition."
>>> balance = principal - tuition
>>> print balance," the amount remaining after first tuition  
>>> deduction.  "
>>> interest = balance * interestRate # calculates the amount added  
>>> to the fund
>>> print interest, "  Interest added to fund for one year. "
>>> newBalance = balance + interest
>>> print newBalance, "is the new balance."
>>> count = 2 # keeps me informed on the number of students  
>>> benefitting from this grant.
>>> while principal > tuition:
>>>  tuition *= tuitionInc # calculates the rising cost of tuition.
>>>  if newBalance < tuition:
>>>    print newBalance + interest
>>>    newBalance = principal
>>>    print principal," is the new balance. "
>>>    interest = principal * interestRate
>>>    print interest," is the new interest on the principal. "
>>>    balance = principal + interest
>>>    print balance,"is the new principal. "
>>>  tuition *= tuitionInc # calculates the rising cost of tuition.
>>>  print tuition," is the new cost of tuition. "
>>>  principal = newBalance - tuition
>>>  print principal," is the new balance. "
>>>  interest = principal * interestRate
>>>  print interest," is the new interest on the principal. "
>>>  balance = principal + interest
>>>  print balance, "is the new principal. "
>>>  count = count + 1
>>>  if tuition > principal:
>>>    print principal + interest, "was available for the last student."
>>> if count > 10:
>>>  print count, "Students used this grant."
>>
>
>
> -- 
> Bob Gailer
> Chapel Hill NC
> 919-636-4239