Dear Allin and Jack,

I think there is a mistake in the mwrite funtion help. According to it:

"If fname has the suffix ".gz" the the file is written with gzip compression. The format is basically as described above except that the matrix elements are written in a single column, in column-major order."

Running the following script and openning testPLAIN and testGZ in a text editor I get the same output (the matrix elements are not written in a single column):

M = {1,2; 3,4; 5,6; 7,8; 9,10}

mwrite(M, "testPLAIN")

mwrite(M, "testGZ.gz")

Best regards,