interest on negative balances

This is a discussion on interest on negative balances within the C++ Programming forums, part of the General Programming Boards category; The last function that I need to write for my Uni assignment is to calculate compound interest. I have done ...

  1. #1
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    Question interest on negative balances

    The last function that I need to write for my Uni assignment is to calculate compound interest. I have done this successfully for balances in credit but I am unsure what to so about balances in debit.

    This is a code excerpt
    Code:
    cout <<"\n\tHow many months to you wish to calculate the interest over? ";
    					cin >> months;
    					double principle = 1000;
    					amount = principal * pow( 1.0 + rate, months );
    					cout <<"\n\tAfter " << months <<" months with a principle of " << principle 
    						 <<"\n\tYour balance will be:"<< setiosflags( ios::fixed | ios::showpoint )<<"\t"
    						 << setprecision( 2 ) << amount <<"\n\n" << endl;
    This works, do I need to make it pow(-1-rate, months) for negative balances?

    Any help would be appreciated.

    ceevee

  2. #2
    & the hat of GPL slaying Thantos's Avatar
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    As far as I know interest is not given on neg balances. A fee might be imposed when you go negative. So a simple check to see if the principle is negative and skipping the interest amount should be enough

  3. #3
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    What I mean is overdraft charges so they are in effect the opposite. I think that I have it figured out now.

    You need 3 algorithms I think.

    The one shown in the code.

    and two for negative balances, one if the power is a even number which is merely pow(-1-rate, months) and one that flips the minus sign if the power is an odd number.

    ceevee

  4. #4
    & the hat of GPL slaying Thantos's Avatar
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    wel if its the same formula:
    If the principle is negative, set a flag to remember that its negative, make the principle positive, if flag is set make negative.

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