gfortran-arm-linux-gnueabihf software package provides GNU Fortran 95 compiler for the armhf architecture, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gfortran-arm-linux-gnueabihf
gfortran-arm-linux-gnueabihf is installed in your system.
Make ensure the gfortran-arm-linux-gnueabihf package were installed using the commands given below,
$ sudo dpkg-query -l | grep gfortran-arm-linux-gnueabihf *
You will get with gfortran-arm-linux-gnueabihf package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Development |
| Package | gfortran-arm-linux-gnueabihf |
| Version | 4:6.1.1-1 |
| Description | GNU Fortran 95 compiler for the armhf architecture |
| Sub Section | devel |