# What is the fastest way to export a large matrix of numbers from MATLAB to Excel (preferably as .xlsx) ?

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Sim on 19 Nov 2022
Commented: Sim on 19 Nov 2022
What is the fastest way to export a large matrix of numbers from MATLAB to Excel (preferably as .xlsx) ?
It looks like there are several ways, such as writematrix, writecell, writetable, xlswrite, csvwrite (apparently, xlswrite and csvwrite are not recommended), etc, but which one is the fastest one for large matrices ?
% Example of matrix of numbers to be exported from Matlab to Excel (preferably as .xlsx):
M = magic(10^3);

Jan on 19 Nov 2022
Edited: Jan on 19 Nov 2022
Simply try it:
M = magic(10^3);
tic;
writematrix(M, 'file1.xlsx');
toc
Elapsed time is 5.094270 seconds.
tic;
writecell(num2cell(M), 'file2.xlsx');
toc
Elapsed time is 10.870852 seconds.
tic;
writetable(table(M), 'file3.xlsx');
toc
Elapsed time is 4.806810 seconds.
tic;
xlswrite('file4.xlsx', M);
Warning: Unable to write to Excel format, attempting to write file to CSV format.
toc
Elapsed time is 0.736247 seconds.
tic;
csvwrite('file5.csv', M);
toc
Elapsed time is 0.481182 seconds.
tic;
fid = fopen('file6.csv', 'W');
fmt = [repmat('%g, ', 1, 999), '%g\n'];
fprintf(fid, fmt, M.');
fclose(fid);
toc
Elapsed time is 0.402371 seconds.
tic;
fid = fopen('file7.csv', 'W');
fmt = [repmat('%g, ', 1, 999), '%g\n'];
fwrite(fid, sprintf(fmt, M.'), 'char');
fclose(fid);
toc
Elapsed time is 0.424347 seconds.
Sim on 19 Nov 2022
It is interesting that, although xlswrite and csvwrite are not recommended, they still outperform the write** functions.
Also, it is interesting that fprintf and fwrite are the fastest solutions available in your tests :-)
Many thanks @Jan!