That depends on the format of your txt-files.
Here is a simple case
%%R2018a
fid = fopen('rugged.txt');
cac = textscan( fid, '%f%f%f', 'CollectOutput',true, 'Delimiter',',' ...
, 'EmptyValue',nan );
fclose(fid);
and
>> cac{:}
ans =
8 1 6
3 5 NaN
4 NaN 2
where rugged.txt contains
8,1,6
3,5,
4, ,2
Upload a short sample txt-file.
