1. simple question

Dear All,
I want to have a code with a formula
N-1 N-1
aut[m]=summation x(n)x(n+m)
n=0 n= 0
if I have code like

Code:
```for (m=0;m<N;m++)
{
for (n=0;n<N;n++)
{
aut[m]+=x(n)*x(n+m);
}
}```
will this work?

2. Have you tried it in a c compiler?
It seems sound enough!

3. Yes, I have complied it, no any error, but the results are out of my expectation. say x(n) is a sequence like:
Code:
`x(n)={1.0,2.0,3.0,3.5}, and N=4.`
when the program runs at some points, take an example , x(5) (when n=3,m=2), the program dont know what value x(5) is? it will return me a radom number which is not i want. How can I solve this problem?
Thank you.

4. Originally posted by lwong
Yes, I have complied it, no any error, but the results are out of my expectation. say x(n) is a sequence like:
Code:
`x(n)={1.0,2.0,3.0,3.5}, and N=4.`
when the program runs at some points, take an example , x(5) (when n=3,m=2), the program dont know what value x(5) is? it will return me a radom number which is not i want. How can I solve this problem?
Thank you.
Whithout code to look at, we can only guess. And my guess is that you've defined x to be an array of 5 values, which means x(0) thru x(4). x(5) does not exist so you are looking at random data outside your array.