function dnac = seqcomplement(dna)
%SEQCOMPLEMENT returns the complementary strand of a DNA sequence.
%
%   SEQ = SEQCOMPLEMENT(DNA) calculates the complementary strand (A-->T,
%   C-->G, G-->C, T-->A) of sequence DNA.
%
%   SEQ is returned in the same format as DNA, so if DNA is an integer
%   sequence then so is SEQ.
%
%   Example:
%
%       % Create a random sequence of nucleotides and the complement.
%       seq = randseq(25)
%       compseq = seqcomplement(seq)
%
%   See also SEQRCOMPLEMENT, SEQREVERSE.

%   Copyright 2003-2004 The MathWorks, Inc.
%   $Revision: 1.4.4.3 $  $Date: 2004/01/24 09:18:58 $

% Full mapping of all nucleotide symbols
% * A C G T(U) R Y K M S W B D H V N
% * T G C A    Y R M K S W V H D B N

% Indices used
% * A C G T(U) R Y K M S  W  B  D  H  V  N
% 0 1 2 3 4(4) 5 6 7 8 9 10 11 12 13 14 15

% If the input is a structure then extract the Sequence data.
if isstruct(dna)
    try
        dna = seqfromstruct(dna);
    catch
        rethrow(lasterror);
    end
end

form = class(dna);
if ischar(dna)
    lowermap = (lower(dna) == dna);
    dna = nt2int(dna);
end
map =  nt2int('*TGCAYRMKSWVHDBN');
dnac = dna;
for count = 1:length(dna)
    dnac(count) = uint8(map(double(dna(count))+1));
end

if strcmp(form,'char')
    dnac = int2nt(dnac);
    dnac(lowermap) = lower(dnac(lowermap));
end