Using switch case and loop in one problem.

This is an interest problem. I have to create a program where the user needs to input an initial deposit amount, the interest rate, and select what the frequency of the compounding is (monthly, quarterly, semiannually, or annually) using a menu. I then need to use a for loop to determine what the amount of money that was accumulated in one year.

so far I have:

I=input('Enter initial deposit amount.');

R=input('Enter interest rate');

freq=menu('Select desired frequency of compounding','Monthly','Quarterly','Semianually','Annually');

I am not sure how to use a switch case and a for loop along with these user inputs. Any suggestions or at least guidance?

Answer 1

[Star Strider]

I suggest that you write the for loop first to be sure it works and calculates the compound interest correctly.

Then read the documentation on switch, case, otherwise and get that working.

Then put them together to create you finished assignment.

[Matthew Quinones]

Alright so for the for loop, I do not need the inputs? Also will I be using the standard compound interest formula?

[Matthew Quinones]

SO far I have:

I=input('Enter initial deposit amount.');

R=input('Enter interest rate');

freq=menu('Select desired frequency of compounding','Monthly','Quarterly','Semianually','Annually');

switch freq

    case 'Monthly'

        disp(12);

    case 'Quarterly'

       disp(4);

    case 'Semiannually'

        disp(2);

    case 'Annually'

        disp(1);

end

for k=freq

    A=I*(1+(R/freq))^freq

end

fprintf('With an initial deposit of %4.0f, an interest rate of %2.2f, and compounding at %2.0f, your accumulated savings in one year is %4.2f.\n',I,R,freq,A)

Now using sample inputs such as I=1000 , R=.05, and the compound being 'Monthly' (selected on the menu), I should be getting the answer $1051.16. Which is the amount accumulated with the given inputs. However, I am getting $1050, and the compound selection is not coming out as a string but as the designated number (1).

Any idea why I can't get the right answer and how to have it display the string instead of the designated menu number?

[Star Strider]

I believe the intent of the assignment is that instead of using the compound interest formula, to do this sort of for loop:

R = 0.05;
freq = 12;
cir = 1 + R/freq;           % Compound interest rate
I = 1;                      % Compounded interest
for k1 = 1:freq
    I = I*cir;
end
P = 1000;
A = P*I;

To check the accuracy, the compounded interest should be between (1+R) and (exp( R )).

To get the output as a string, use a cell array:

freqstr = {'Monthly','Quarterly','Semianually','Annually'};
fprintf('\nCompounding Frequency: %s\n', freqstr{3})

[Matthew Quinones]

now how about for the other frequencies? Do I have to do a for loop for each one?

[Star Strider]

Not necessarily. Once you have the interest rate R and the compounding period freq, you can run the loop once at the end of switch...case...end block. Then print the result.