How to put a string in a text file to define headers to data?

Here is my code. I'm trying to make a header for columns of data, but everytime I run only the data remains in the file. Please help! Thanks.

for k=1:3
filename1=sprintf('s%d.txt',k);
 
fprintf(filename1, '# GHz S DB 50');
for j=1:3
M(j,1) = k;
M(j,2) = k;
M(j,3) = k;
 
dlmwrite(filename1,M,'-append','delimiter','\t'); 
end
end

[Bob Thompson]

Are you sure the headers are printing in the first place? Typically when I print headers for data I end up needing to open the file with fopen before the headers will print for me.

[Alexandria Will-Cole]

It's not. I am asking how to do so. Thanks!

Answer 1

[Jeremy Hughes]

The issue is here:

fprintf(filename1, '# GHz S DB 50');

fprintf doesn't accept a file name, it need an open, writable file-id

fid = fopen(filename1,'w');

fprintf(fid, '# GHz S DB 50');

fclose(fid);

Then things should work as you expect