Mat files saved by MFL cannot be read by Octave

[grabarczyk-t]

I have problem reading files saved with MFL when using Octave. I saved a simple mat file, as instructed in the readme:

MatFile matFile = Mat5.newMatFile()
	.addArray("var1", Mat5.newScalar(7));
Mat5.writeToFile(matFile, "data.mat");

and when I try to read it in Octave using load('data.mat'), I get an error:

error: load: failed to read matrix from file 'data.mat'

The file loads fine in Matlab.

I didn't have such problem when I was using MatFileRW library.

[ennerf]

That's odd. I've never used Octave, but I wouldn't expect any problems with simple files like this.

I'll get Octave and see if I can reproduce the issue.

[grabarczyk-t]

Ok, thanks. For the record I used Octave version 3.6.4

[ennerf]

Actually, I'm having issues downloading it. Could you provide an equivalent .mat file generated with your version of Octave?

[grabarczyk-t]

Yes, sure. Here is equivalent file saved in my Octave: data-octave.mat I saved it like that:

var1 = 7; 
save('data-octave.mat', '-mat', 'var1')

Here is also equivalent file written with MatFileRW library: data-matFileRW.mat

[ennerf]

I believe I've found a possible issue. A missing subsysOffset is erroneously written as -1 while MATLAB and MatFileRW default to 0. I assume that this is tripping up the Octave reader, although it is weird that Octave itself initializes this to a garbage value 2314885530818453536. Maybe it requires a positive value?

PR #50 has a potential fix for this. Please check if Octave can load data-mfl-subsys-fix.mat.

The full header information is below:

mfl-le: Mat5File{description='MATLAB 5.0 MAT-file, Platform: Windows 10, Created on: Wed Aug 28 11:13:24 CEST 2019', subsysOffset=-1, byteOrder=LITTLE_ENDIAN, version=1}
mfl-be: Mat5File{description='MATLAB 5.0 MAT-file, Platform: Windows 10, Created on: Wed Aug 28 11:20:12 CEST 2019', subsysOffset=-1, byteOrder=BIG_ENDIAN, version=1}
matFileRW: Mat5File{description='MATLAB 5.0 MAT-file, Platform: Windows 10, CREATED on: Wed Aug 28 11:33:15 CEST 2019', subsysOffset=0, byteOrder=BIG_ENDIAN, version=1}
matlab: Mat5File{description='MATLAB 5.0 MAT-file, Platform: PCWIN64, Created on: Wed Aug 28 11:22:35 2019', subsysOffset=0, byteOrder=LITTLE_ENDIAN, version=1}
octave: Mat5File{description='MATLAB 5.0 MAT-file, written by Octave 3.6.4, 2019-08-28 09:30:46 UTC', subsysOffset=2314885530818453536, byteOrder=LITTLE_ENDIAN, version=1}

[grabarczyk-t]

I checked that file and it loads correctly on my Octave

[ennerf]

Ok. Thanks for your help. I'll get a new bugfix release out shortly.

[ennerf]

Version 0.5.4 has been released to maven central