Calculate the number of years the money will last?

my program is supposed to calculate the # of years the money will last for each retiree.. each year 2.5% interest is added onto the balance and the individuals withdraws 4.5%. So i created a While loop but the loop just keeps repeating, it doesn't stop. I think my main problem is that i dont no what to write for the conditional statement of While loop. Here's what i have so far

No_of_elements = 7;% the number of retirees 
min_years = 40; 
max_years = 50;

*% # of years of employment
r = round(min_years + (max_years-min_years).*rand(No_of_elements,1))
% deposit '
x = (400000-300000 * r-min(r)) ./ max(r) - min(r) + 300000

W = 0; % the initial withdrawal amount 
years = 0;

while x >= W
    format bank 
% the interest 
i = x*0.025
% the balance after the interest is added 
B= x+i
% the amount of withdrawal 
W = B*0.045
% the balance after the withdrawal 
x = B-W
years = years+1;
if x<=0  
    fprintf ('the number of years: %d \n',years)
end 
end

[Jonathan Campelli]

I'm having difficulty discerning what the variable 'Z' refers to. It has not been initialized anywhere in the above code. Thanks for cleaning it up too, James.

[nada Elmoghany]

oh sorry about that, that was a typo.. its supposed to W not Z, and the B1 is supposed to B. Sorry

[dpb]

Suggest you then edit your code to reflect the changes...

Answer 1

[Jonathan Campelli]

Nada, your While loop was not breaking because your x values were never reaching zero. I've crafted a nested while loop that stops looping when your "bank account" dips below 1 Cent, or $0.01:

No_of_elements = 7;% the number of retirees 
min_years = 40; 
max_years = 50;

r = round(min_years + (max_years-min_years).*rand(No_of_elements,1)) % deposit ' 
x = (400000-300000 * r-min(r)) ./ max(r) - min(r) + 300000

W = 0.01; % the initial withdrawal amount 
years = zeros(1,numel(x))';

for count=1:numel(x)
    while x(count)>W
     x(count)=x(count)+(x(count)*0.025)-(x(count)*0.045);
     years(count)=years(count)+1;
    end
end

years

[nada Elmoghany]

Thank you very much for your help... That question was honestly frustrating me. Thanks again

[Jonathan Campelli]

You're welcome. I'm glad I could be of help.