sums with for loop

I am beginner in matlab, and i struggly to resolve some exercice. can I have some advice according to this task?

1-1/3+1/5-1/7+1/9-..-1/1003

Answer 1

[David Hill]

n=1:502;
s=sum((-1).^(n+1)./(2*n-1))

s = 0.7849

[Alonso Mukendi Kalonji]

how did you get 502 for the loop

[VBBV]

The highest term in the fraction of series is 1003. So it can obtained by this way 2*502-1

[David Hill]

2*502 -1 = 1003 (last element). 2*n-1 is an expression for odd numbers.

[Alonso Mukendi Kalonji]

This cod are not working

>> a = 1;

k = 502;

for x = 1:k

s = sum(((-1).^(x+1))./(2*(x-1)));

end

disp(s)

-9.9800e-04

[David Hill]

No need for a loop. Just run the below code.

x=1:502;
s=sum((-1).^(x+1)./(2*x-1))

s = 0.7849

[Torsten]

Maybe of interest:

syms n
s = simplify(symsum((-1)^n/(2*n+1),0,Inf))

s = 

[Alonso Mukendi Kalonji]

I get it!

Thank you very much!