gdl-mpfit software package provides Robust non-linear least squares curve fitting for GDL, 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 gdl-mpfit
gdl-mpfit is installed in your system.
Make ensure the gdl-mpfit package were installed using the commands given below,
$ sudo dpkg-query -l | grep gdl-mpfit *
You will get with gdl-mpfit package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Science |
| Package | gdl-mpfit |
| Version | 1.84+2016.05.19-1 |
| Description | Robust non-linear least squares curve fitting for GDL |
| Sub Section | Science |