Subscript indices must either be real positive integers or logicals. Error

So I am trying to write some code where I basically loaded in a file:

n=[0:1:1000];
x=file (with data);
y(n)= x(n)-x(n-3)

Matrix: size of x: 2000X1 size of n: 1X2000

I receive that error when I try to run the program. The file name data has the data listed like [1 [1.1 [1.4 [1.5 [1.8]

I am stuck on how I would rid of the error

Answer 1

[Star Strider]

The problem is here:

n=[0:1:1000];

and here:

x(n-3)

Zero is not a positive integer, and any value of (n < 4) will also not work.

Possible solution:

1. Define n=[4:1:1000]; and
2. Define x(1:3) outside your (implied) n-loop