gistfile1.txt

-module(khf1).
-author('najibg96@gmail.com').
-vsn('2017-10-17').
-export([cella/2]).
  	
cella(S, I) ->
	M = length(S),
	K = trunc(math:sqrt(M)),
	IS = (((I-1) div K) * K) + 1,
	JS = (((I-1) rem K) * K) + 1,
	SL = lists:sublist(S, IS, K),
	lists:flatten(transpose([lists:sublist(L, JS, K) || L <- SL])).

transpose([[]|_]) -> [];
transpose(M) ->
  [lists:map(fun hd/1, M) | transpose(lists:map(fun tl/1, M))].