Introduction

New features can often be introduced in SKIRT without affecting existing ski files. For example, a new geometry, material mix, wavelength grid, and so forth can easily be added as a new option in the list without any effect on existing parameter files. Similarly, a new scalar property can be added as long as a default value is provided that reproduces the previous behavior.

Sometimes, however, a new feature requires a more significant change. This can involve renaming entities or moving them around to different places in the ski file structure. In this case, running an existing ski file may cause the new SKIRT version to produce a fatal error while reading the parameter file and constructing the simulation.

The list of Recent changes highlights the SKIRT updates where such incompatible changes occurred.

Upgrading parameter files

When faced with an incompatible ski file update of SKIRT, proceed as follows:

git pull and build the most recent SKIRT version (you probably did this already)
git pull the most recent PTS version (to install the latest version of the upgrade procedure)

Then change to the directory containing the ski file(s) you wish to upgrade and enter the command:

pts upgrade_ski .

To process ski files in another directory, replace the . by that directory's path. In both cases, backup copies of the original ski files are placed in the same directory (with a filename including a time stamp) before the upgrade is performed.

If you don't have PTS installed, there are two options:

In simple cases, and when you know the details of the update, you can manually adjust the ski file in a text editor.
Worst case, you can reconstruct the desired configuration in a fresh parameter file by performing the full interactive Q&A, either on the command line or using MakeUp.