Yenny, hi
N-grams (in WordSmith) are computed like this. With a piece of text
containing say
My uncle used to work for the BBC
when computing 3-grams, the program stores these sequences
my uncle worked
uncle worked for
worked for the
for the BBC
thus using a moving 3-word window. It may also decide whether to take
note of sentence or other breaks as it works. As it works, it sorts
and if it finds a repeat it adds to a suitable counter. After it
finishes, the program counts how many of each sequence it found and
then saves them for the user to see.
I hope that helps. You will find more WordSmith help explanation at
http://www.lexically.net/downloads/version6/HTML/index.html?wordlist_clusters.htm
Best -- Mike