function pos = findPattern(dna,pat)

% Post: pos contains a vector of the positions at which pat appears in dna 

% Pre: Vector dna contains an array of DNA nucleotides.

% pat contains a pattern of nucleotides 





pos= [];  % vector of locations where 'GGT' occurs



lenPat = length(pat); 



for k= 1: length(dna)-lenPat +1

    % Check to see if pat  is the same substring as 

    % dna(k:k+lenPat-1) 

    % We do this in a non vectorized way first 

    i=1; 

    while( i<= lenPat && dna(k+i-1) == pat(i) ) 

      i = i+1; %increment the index i until we find a difference

    end

    

    if (i==lenPat+1)  % all entries coincided

        pos = [pos k]; % add position k to the list 

    end

              

end