Is it possible to create a tall array from a .mat file which contains only 1 variable?

Hi, I've read the documentation about tall array and they usually create one on top of a datastore:

ds = datastore(file_name);
tt = tall(ds);

with the datastore created from a .csv. I know other formats, such as text, are supported,but from what I've experimented a .mat file with only 1 matrix is much smaller than a text file or a .csv file containing the same variable, therefore I want to create a tall array from a .mat file which contains only 1 variable. Is it possible? Here is actually what I'm trying to do:

I want to work on the "webspam" dataset in libsvm: https://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/binary.html . Some information: # of data: 350,000 # of features: 16,609,143 . And I want to create a dense matrix with size(16609143,48), then I want to multiply the data with this matrix, so I'd like to do that with tall array? Can anyone help me? Thank you very much :)

[Juan Estrella-Martínez]

Did you ever solve this mate?