Question about to reconduct [for loop statement] to the code using vectorization

hello

first i made the code that he answer to the following expression is 0.7849

its expression is

the code i made is (result is 0.7849)

sum=0;

for m=0:2:10000000

k=m;

i=m+1;

sumx=(1/(2*k+1));

sumy=(-1/(2*i+1));

sum=sumx+sumy+sum

end

-----------------------------------------------------------------------------------------------

So, What I want to do is to reconstruct the code above using vectorization.(use ./ .*) (not using for loop statement)

i made this, but it works strangely.(I don't know if I made it right)

format short

sum=0;

m=0:2:500;

k=m;

i=m+1;

sumx=(1./(2*k+1));

sumy=(-1./(2*i+1));

sum=sumx+sumy+sum

Should I write more variable?

How do I reconstruct it right?

[VBBV]

format short
sumi=0; % sum is builtin function of matlab
m=0:2:500;
k=m;
i=m+1;
sumx=sum((1./(2*k+1)));  % apply the sum function to the series 
sumy=sum((-1./(2*i+1))); % sum the series
Sum=sumx+sumy+sumi

Sum = 0.7849

sum is a builtin function in matlab, variables are usually named that doesnt conflict with standard builtin functions in matlab,

[N/A]

@VBBV

i did simillar as you did, but it didnt work because i used 'sum' function as it.

after seeing this, i found my fault.

thanks!

Answer 1

[David Hill]

format long
s=sum(1./(2*(0:2:500)+1)-1./(2*(1:2:501)+1))

s = 
   0.784900155923366