While Loop Problem Displaying NaN

So I am trying to make a while loop which finds the value of log(x+1) using a taylor series. I am having the series run until the answer comes into a certain precision. When I run the function with x=1 I get the correct out for both y and i. However if I try it with any greater number the y value displays as NaN. Can anyone help me figure out how to fix this.

function logoneplusx(x)
format long
y=0;i=1;Err=1;
while Err>0.001
  y=((-1)^(i-1))*((x^i)/i)+y;
  i=i+1;
  Err=abs(y-log(x+1));
end
disp(y)
disp(i)

Answer 1

[Azzi Abdelmalek]

When x is bigger, y becomes infinite, and after you have Err=(inf-inf)=NaN. Matlab or another software has its limits.

[Dan]

but ln(5)=1.6... this is not even close to inf

Answer 2

[James Tursa]

If you check this link, you will see that the series you are using only converges for abs(x) <= 1 and x not equal to -1:

http://en.wikipedia.org/wiki/Natural_logarithm

If you want to use an x value outside this convergence range, use a different series. On this same link there is another series you can use for other values of x.