gfortran-6-multilib-mips64-lin software package provides GNU Fortran compiler (multilib support), 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-6-multilib-mips64-lin
gfortran-6-multilib-mips64-lin is installed in your system.
Make ensure the gfortran-6-multilib-mips64-lin package were installed using the commands given below,
$ sudo dpkg-query -l | grep gfortran-6-multilib-mips64-lin*
You will get with gfortran-6-multilib-mips64-lin package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Development |
| Package | gfortran-6-multilib-mips64-lin |
| Version | 6.1.1-9cross1 |
| Description | GNU Fortran compiler (multilib support) |
| Sub Section | devel |