MATLAB mex not looking for compiler gfortran on macOS

Question

I need to call some Fortran code from within MATLAB. I did some research and read about the mex command and how to use it. Sadly I'm already failing at getting the Fortran compiler to work.

First of all, here's my setup:

macOS Sierra 10.12.1 (latest version)
MATLAB R2016b (latest version)
gfortran 4.9.2 (installed via .dmg from official GNU site)

According to the MATLAB documentation, I can use mex -setup FORTRAN to prepare mex for building a mex-file from Fortran. However, running the command in verbose mode yields the following output: mex -setup -v FORTRAN

Verbose mode is on.
... Looking for compiler 'Intel Fortran Composer XE' ...
... Looking for environment variable 'IFORT_COMPILER16' ...No.
... Looking for environment variable 'IFORT_COMPILER15' ...No.
... Looking for environment variable 'IFORT_COMPILER14' ...No.
... Looking for environment variable 'IFORT_COMPILER13' ...No.
... Executing command 'which ifort' ...No.
Did not find installed compiler 'Intel Fortran Composer XE'.
Error using mex
No supported compiler or SDK was found. For options, visit
http://www.mathworks.com/support/compilers/R2016b/maci64.html.

Following the link, one can see that MATLAB does support GNU gfortran 4.9.x on Linux. On Mac however, only Intel's commercial compilers are listed as supported. That's what mex seems to be looking for as well.

Since Mac can also use gfortran to compile Fortran code I thought it'd be possible to get it to work with MATLAB. I've also googled alot and found questions like this one on the MathWorks forum, which suggests that MATLAB should be able to use gfortran, even on Mac.

That's what I think is strange, my MATLAB isn't even looking for a gfortran compiler. All it does is look for an Intel compiler, can't find one and then throws above stated error message.

Regarding my gfortran installation. It is definitely 4.9.2 (which is listed as supported under Linux), which gfortran returns /usr/local/bin and I can successfully compile programs via Terminal.

By the way, mex -setup ANY successfully lists the compilers for C and C++ but no Fortran.

MEX configured to use 'Xcode with Clang' for C language compilation.
Warning: The MATLAB C and Fortran API has changed to support MATLAB
 variables with more than 2^32-1 elements. In the near future
 you will be required to update your code to utilize the
 new API. You can find more information about this at:
 http://www.mathworks.com/help/matlab/matlab_external/upgrading-mex-files-to-use-64-bit-api.html.
MEX configured to use 'Xcode Clang++' for C++ language compilation.
Warning: The MATLAB C and Fortran API has changed to support MATLAB
 variables with more than 2^32-1 elements. In the near future
 you will be required to update your code to utilize the
 new API. You can find more information about this at:
 http://www.mathworks.com/help/matlab/matlab_external/upgrading-mex-files-to-use-64-bit-api.html.

To choose a different C compiler, select one from the following:
Xcode with Clang  mex -setup:'/Users/Lennart/Library/Application Support/MathWorks/MATLAB/R2016b/mex_C_maci64.xml' C
Xcode Clang++  mex -setup:'/Users/Lennart/Library/Application Support/MathWorks/MATLAB/R2016b/mex_C++_maci64.xml'

I also had a look at those .xml files mentioned at the very end of the last output. There was no file for anything having to do with Fortran and I wasn't able to successfully write one myself. I'm not even sure whether that's the problem...

So simply put my question is: How can I get MATLAB to actually look for and then of course also find my gfortran compiler to use it to compile mex files?

Appreciate your help!

lerei · Accepted Answer

Thanks to hsuyaa and the provided link I was able to resolve my problem. As it needed some more experimenting by myself, I'd like to post how exactly I was able to get gfortran to work.

Look at this link and the accepted answer. Although the MathWorks Team explicitly states that the instructions are specifically written for xCode 7.0 and MATLAB R2015b, I got everything to work with xCode 8.1, MATLAB R2016b and macOS Sierra 10.12.

MATLAB seems to be storing the compiler configuration details in .xml-files as mentioned before. You can find the directory in MATLAB by entering

cd( fullfile( matlabroot, 'bin', 'maci64', 'mexopts' ) );

I did perform a fresh install of MATLAB before but at that location, only three files where located, one for Clang, one for Clang++, one for Intel's Fortran. The gfortran one was simply missing.

The solution author at MathWorks appended all of these .xml-files to his post. I downloaded the files and copied gfortran.xml to the above mentioned folder. This granted partial success in that it made MATLAB actually look for gfortran when running the mex setup.

However, since the files are not up-to-date, I had to add a few lines. I don't exactly understand how the configuration files work, but I noticed that some lines where referring to older macOS versions. Download the file gfortran.xml behind the above link and then add the following:

Wherever you see

or

also add

or

macOS 10.12 is Sierra. Saving the file and running mex -setup FORTRAN again successfully identified gfortran and set it as the fortran compiler for mex.

MATLAB mex not looking for compiler gfortran on macOS

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