Fortan Compiler for Apple Silicon (M1, M2, M3)

GNU Fortran (GFortran) is excellent on Apple Silicon. Easily installed via Homebrew (brew.sh) at the command line. I do all of my Fortran development and testing on Apple Silicon, before moving to Linux AMD and Intel clusters. It follows all the same/usual standards, is kept updated with the current version, and the performance per core is brilliant.

I have been using the llvm compiler on a M2 MacBook Pro with some success. Results are different than the same scientific code on other platforms/compilers though. I have not been able to figure that out. I could not get NAG fortran to work very well. Another member of our group successfully compiled our code using NAG on an Intel-based mac but I could not do so on the ARM M2 chip

That sounds like a great use for an old Apple II.

There is a trial NAG Fortran compiler for Apple Silicon (ARM) Macs. It is not free, I don't use it, and you will need to talk with NAG about any limitations it may have on M1/2/3 Macs and associated library compatibility. It is my understanding that GNU is not targeting their Fortran development for Apple Silicon Macs.

Thank you for the excellent information regarding GNU Fortran compiling platform. I'm a newbie at code writing and compiling and I apologize for asking this, but where do I get the GNU Fortran compiling binaries? I am using Apple M1 and M2 Silicon and am really in need of a Fortran compiler to compile the molecular dynamics software code, AMBER. Any information you can provide to help would be very thankfully received.

Your order of installation:

1. You will need the homebrew (brew) package manager. See brew.sh and copy/paste the installation script line into the Terminal and press return.
   1. It will detect that it needs to install the Apple command-line tools for Xcode and do that. This is needed in order to build Apple Silicon binaries of the packages it installs
2. On Apple Silicon Macs, homebrew will want to install into /opt/homebrew and binaries will be written into /opt/homebrew/bin.
   1. In your Bash or Zsh shell dot file, set export PATH="${PATH}:/opt/homebrew/bin"
   2. This will allow your SHELL to find the GNU bits after they are installed

There is no such thing as getting just the GNU fortran compiler. You must install the monster GNU C/C++ build and all of its libraries in order to get gfortran.

After you have installed homebrew, and while still in the Terminal, you want to do the following:

brew outdated
brew upgrade (if anything is shown as needing upgraded from the outdated command)
brew install gfortran
brew cleanup

The GNU Fortran documentation is online.

Your order of installation:

1. You will need the homebrew (brew) package manager. See brew.sh and copy/paste the installation script line into the Terminal and press return.
   1. It will detect that it needs to install the Apple command-line tools for Xcode and do that. This is needed in order to build Apple Silicon binaries of the packages it installs. It does not install Xcode.
2. On Apple Silicon Macs, homebrew will want to install into /opt/homebrew and binaries will be written into /opt/homebrew/bin.
   1. In your Bash or Zsh shell dot file, set export PATH="${PATH}:/opt/homebrew/bin"
   2. This will allow your SHELL to find the GNU bits after they are installed

There is no such thing as getting just the GNU fortran compiler. You must install the monster GNU C/C++ build and all of its libraries in order to get gfortran. Even on M1/M2 Macs, that will take awhile to build.

After you have installed homebrew, and while still in the Terminal, you want to do the following:

brew outdated
brew upgrade (if anything is shown as needing upgraded from the outdated command)
brew install gfortran
brew cleanup

The GNU Fortran documentation is online.

And there is the work-in-progress Flang project (Fortran 2018) under the auspices of LLVM which in their own words, is "not ready for production usage", but is in active development. It is free and has an Apache license. It is written in contemporary C++ and takes Fortran code to an executable.

LLVM-Project: Flang

Having not written any production Fortran code in decades, I have not built/installed Flang myself.

> And there is the work-in-progress Flang project (Fortran 2018)...

There is also a "Classic Flang" compiler based on an older version of pgfortran. It's eventually supposed to be replaced by the Fortran 2018 Flang, mentioned by VikingOSX.

I haven't used any of them, I'm just trying to be helpful :-)

these days you can proably get an apple II emulator for most macOS or windows or linux operating systems

Thank you so much for the information about homebrew and GNU. I appreciate your help with that issue.

Viking, where will I acquire the homebrew package?