How to load data from Octave?

I have a .M file from Octave that I want to run in MATLAB, but I obtain an error. Here is the content of .M file (it's just one line):

load "Slovenia_centered.mat"

And here is the error:

Error using load
Unable to read file '"Slovenia_centered.mat"': Invalid argument.

Error in 
Slovenia_centered (line 1)
load "Slovenia_centered.mat"
^^^^

Answer 1

[dpb]

d=dir('Slovenia_centered.mat')

d = struct with fields:
       name: 'Slovenia_centered.mat'
     folder: '/users/mss.system.hwgbc'
       date: '13-Feb-2026 16:09:15'
      bytes: 8972
      isdir: 0
    datenum: 7.4003e+05

type Slovenia_centered.mat

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Aha! It's text, not native .mat.

x=load('-ascii','Slovenia_centered.mat')

x = 545×1

0.2436 0.0434 -0.1123 -0.2285 -0.1911 -0.2707 -0.3114 -0.3503 -0.0665 -0.0091 -0.0821 -0.1782 -0.2971 -0.2469 -0.2194

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

To write data from Octave to be imported into MATLAB, it would be more portable to either explicitly write text data with fprintf or whatever other higher-level functions Octave has implemented in parallel with MATLAB or as native binary data with fwrite to read with fopen and fread

Although, presuming Octave has it implemented, if it can write a specific version of a .mat file that has the benefit of also storing the variables and shape and type information that alternate forms don't without extra effort. Just have to be sure to write in a known version and then verify it does work as expected (not that I have any reason to think it wouldn't; Octave has been around for a long time).

[Svit]

Thank you so much dpb. One further question. I need the data not in one column, but in five columns, such as in the attached file Slovenia. The data include observations of five variables: consumption, investment, interest rates, inflation rate and monetary aggregate M3. How could I split the data in multiple columns? I searched the questions on this forum, as well as on Google and AI (Copilot), but I haven't found anything useful.

My code looks like this, it includes temp variable that includes five types of data:

temp = [ data];
Dataslpiobs=temp(:,1);
Dataslinobs=temp(:,2);
Dataslcobs=temp(:,3);
Dataslrobs=temp(:,4);
Dataslmobs=temp(:,5);

Your help is much appreaciated!

[dpb]

I moved to continue the same thread -- dpb

That depends on how the data were written...let's see what the file actually contains...

%type Slovenia
Slovenia
whos

  Name               Size            Bytes  Class     Attributes

  Dataslcobs       109x1               872  double              
  Dataslinobs      109x1               872  double              
  Dataslmobs       109x1               872  double              
  Dataslpiobs      109x1               872  double              
  Dataslrobs       109x1               872  double              
  ans                1x34               68  char                
  temp             109x5              4360  double              

Well, we have five variables each of whch is a vector and another that is an array of the composite size of the others...one presumes that was created from them?

OK, now see what was mentioned in the comment...

vnames={'Dataslcobs','Dataslinobs','Dataslmobs','Dataslpiobs','Dataslrobs'};
tData=array2table(temp,'VariableNames',vnames);
head(tData)

    Dataslcobs    Dataslinobs    Dataslmobs    Dataslpiobs    Dataslrobs
    __________    ___________    __________    ___________    __________

      0.067         0.037379       0.18434       31.625         0.11012 
      0.039        -0.098394     -0.015834        16.43        0.072263 
      0.042         -0.20897       -0.1716       17.254        0.014422 
       0.06         -0.29284      -0.28771       28.034       -0.032916 
      0.039         -0.10147      -0.25037       19.002       0.0049062 
      0.047         -0.20429      -0.32994       18.277       -0.054305 
      0.037          -0.2644      -0.37067       16.178       -0.078131 
      0.046         -0.31964      -0.40951       21.855        -0.11888 

OTOH, if you have a (again text) .mat file that is the temp array, then you could read it into the table directly as

fn='OctaveArrayDataFile.mat';   % assume text file
tData=readtable(fn,'FileType','text','VariableNames',vnames);

where like with load have to tell MATLAB a .mat file is in text format rather than native form.

You can then apply all the power of MATLAB to the table referencing each by name with whatever it is that is wanted to be done.

The Q? is how are you getting these .mat files -- are you creating them yourself or is somebody providing them? Can you (or they) change how they're being written to save as -V7 MATLAB .mat files in which case you'll get the variable names and sizes automagically.

What specifically is to be done might aid in other more specific recommenations.

Answer 2

[dpb]

load "Slovenia_centered.mat"

Using the command syntax the filename is text already so it's including the apostrophes as well...try

load Slovenia_centered.mat

I'm not sure about what level for .mat file compatibility Octave supports, you may need to check there about ensuring .mat files.

[Stephen23]

Yes. The documentation explains why using double quotes will fail with command syntax, it has whole section entitled "Why Does Using Command Form With Strings Return An Error?":

https://www.mathworks.com/help/matlab/matlab_prog/frequently-asked-questions-about-string-arrays.html#mw_c5847aac-8745-4fb1-997a-4fc5c324fffb

The gist of it is "In command form, double quotes are treated as part of the literal text rather than as the string construction operator". This is to be consistent with how command syntax has always worked.

[dpb]

BTW, to complete the picture

load("Slovenia_centered.mat")

will also work because as an argument the "" are constructors and the underlying char string will be passed.

[Stephen23]

According to the Octave SAVE documentation

https://octave.sourceforge.io/octave/function/save.html

its default is to "Save the data in Octave’s text data format. (default)." Apparently it also has options to save in formats which are MATLAB compatible.