15 Apr 2015

# Unicode and Matlab on the command line

As per the latest Stackoverflow Developer Survey, Matlab is one of the most dreaded tools out there. I run into Matlab-related trouble daily. In all honesty, I have never seen a programming language as user-hostile and as badly designed as this.

So here is today's problem: When run from the command line, Matlab does not render unicode characters (on OSX).

I say "(on OSX)", because on Windows, it does not print a damn thing. Nope, no disp output for Windows users.

More analysis: It's not that Matlab does not render unicode characters at all when run from the command line. Instead, it renders them as 0x1a aka SUB aka substitute character. In other words, it tries to render unicode as ASCII (which doesn't work), and then replaces all non-ASCII characters with SUB. This is actually reasonable if Matlab were running on a machine that can't handle unicode. This is not a correct assessment of post-90s Macs, though.

To see why Matlab would do such a dastardly deed, you can use feature('locale') to get information about the encoding Matlab uses. On Windows and OS X, this defaults to either ISO-8859-1 (when your locale is pure de_DE or en_US) or US-ASCII, if it is something impure. In my case, German dates but English text. Because US-ASCII is obviously the most all-encompassing choice for such mixed-languages environments.

But luckily, there is help. Matlab has a widely documented (not) and easily discoverable (not) configuration option to change this: To change Matlab's encoding settings, edit %MATLABROOT%/bin/lcdata.xml, and look for the entry for your locale. For me, this is one of

<locale name="de_DE" encoding="ISO-8859-1" xpg_name="de_DE.ISO8859-1"> ...
<locale name="en_US" encoding="ISO-8859-1" xpg_name="en_US.ISO8859-1"> ...


In order to make Matlab's encoding default to UTF-8, change the entry for your locale to

<locale name="de_DE" encoding="UTF-8" xpg_name="de_DE.UTF-8"> ...
<locale name="en_US" encoding="UTF-8" xpg_name="en_US.UTF-8"> ...


With that, Matlab will print UTF-8 to the terminal.

You still can't type unicode characters to the command prompt, of course. But who would want that anyway, I dare ask. Of course, what with Matlab being basically free, and frequently updated, we can forgive such foibles easily…