You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: opt_fft_size.m
    path of file: ./repos/IRCNN/utilities
    
    the code of the file until where you have to start completion: function m = opt_fft_size(n)
% opt_fft_size.m
%
%   compute an optimal data length for Fourier transforms
%
%     written by Sunghyun Cho (sodomau@postech.ac.kr)
%
persistent opt_fft_size_LUT;

LUT_size = 4096;

if isempty(opt_fft_size_LUT)
    fprintf('generate opt_fft_size_LUT\n');
    opt_fft_size_LUT = zeros(LUT_size,1);

    e2 = 1;

    
function m = opt_fft_size(n)
% opt_fft_size.m
%
%   compute an optimal data length for Fourier transforms
%
%     written by Sunghyun Cho (sodomau@postech.ac.kr)
%
persistent opt_fft_size_LUT;

LUT_size = 4096;

if isempty(opt_fft_size_LUT)
    fprintf('generate opt_fft_size_LUT\n');
    opt_fft_size_LUT = zeros(LUT_size,1);

    e2 = 1;
    while e2 <= LUT_size
        e3 = e2;
        while e3 <= LUT_size
            e5 = e3;
            while e5 <= LUT_size
                e7 = e5;
                while e7 <= LUT_size
                    if e7 <= LUT_size
                        opt_fft_size_LUT(e7) = e7;
                    end