使用M函数：mat2huff，huff2mat，实现huffman编码和解码.请使用matlab实现

下面是mat2huff和huff2mat函数的代码实现，以及一个简单的示例：

function huff = mat2huff(mat)
% MAT2HUFF converts a matrix into a Huffman encoding
% huff = mat2huff(mat)
% mat: input matrix
% huff: output Huffman encoding

% Calculate symbol probabilities
symbols = unique(mat);
prob = histc(mat(:), symbols) / numel(mat);

% Build Huffman tree
[~, ~, code] = hufftree(prob);

% Encode matrix using Huffman code
huff = cell(size(mat));
for i = 1:numel(mat)
    idx = symbols == mat(i);
    huff{i} = code{idx};
end
huff = cat(1, huff{:});

end

function mat = huff2mat(huff, symbols)
% HUFF2MAT decodes a Huffman encoding into a matrix
% mat = huff2mat(huff, symbols)
% huff: input Huffman encoding
% symbols: vector of symbols used to generate Huffman code
% mat: output matrix

% Build Huffman tree
prob = histc(symbols(:), symbols) / numel(symbols);
[~, idx, ~] = hufftree(prob);

% Decode Huffman code using tree
mat = zeros(size(huff));
currnode = idx(end);
for i = 1:numel(huff)
    if huff(i) == '0'
        currnode = idx(currnode, 1);
    else
        currnode = idx(currnode, 2);
    end
    if isempty(idx(currnode, 1)) && isempty(idx(currnode, 2))
        mat(i) = symbols(currnode);
        currnode = idx(end);
    end
end
mat = reshape(mat, size(huff, 1), []);

end

% Example usage
mat = [1 2 3; 3 2 1];
huff = mat2huff(mat);
mat2 = huff2mat(huff, unique(mat));
assert(isequal(mat, mat2));

在这个示例中，我们将一个2x3的矩阵编码为Huffman编码，然后解码回原始矩阵。mat2huff函数将矩阵转换为Huffman编码，huff2mat函数将Huffman编码解码为矩阵。