Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
All three patterns contain 11 × 11 dots spaced on a regular grid with individual dot positions independently perturbed by addition of a random positional shift. (a) The random perturbation is so small as to be invisible. (b) It is twice as great and just visible. (c) It is twice that of the middle panel and is clearly visible.
