How to find the partial sum of the series using while loop?

I need to find the partial sum of the series S=1/n for n=5 using while loop.

n = 1 ;

s = 0 ;

while n<=5;

s = s+1/n ;

end

s

I tried using this code I have but matlab won't run. I am not sure what i am doing wrong.

Answer 1

[DGM]

Using a while loop when the number of iterations is known is an unnecessary invitation for mistakes like that. You weren't incrementing n, so the loop would never exit. Just use a for-loop if you must use a loop.

s = 0 ; 
for n = 1:5
    s = s+1/n ; 
end
s

s = 2.2833

If you don't need to use a loop, then things can be simplified.

s = sum(1./(1:5))

s = 2.2833

[Teb Keb]

I am required to use while loop. I already figured out the for loop. But somehow, I just don't know how to write while loop :(

[DGM]

s = 0 ; 
n = 1;
while n<=5
    s = s+1/n ; 
    n = n+1; % increment
end
s

s = 2.2833

[Teb Keb]

oh wow. thank you so much!

Answer 2

[Image Analyst]

To get the partial sums (sums that depend on what element you're at), you can use cumsum()

n = 1 : 5;
s = cumsum(1 ./ n)

s = 1×5

1.0000 1.5000 1.8333 2.0833 2.2833

This is the "vectorized" way of doing it that most MATLAB programmers would use. s(end) is the final/last sum for all 5 elements. Or in the while loop

s = 0 ; 
n = 1;
while n <= 5
    s(n) = s(end) + 1 / n ; 
    n = n + 1; % Increment n
end
s(end)

ans = 2.2833

[Teb Keb]

thank you!