There are two reasons to look at the code. The first is to look for bugs. Obviously that is easier if you have the code. Testing is much easier than writing fro

There are two reasons to look at the code. The first is to look for bugs. Obviously that is easier if you have the code. Testing is much easier than writing from scratch. The second is to see how robust the results are to changes in assumptions and other aspects of the methodology. When you are talking about a big computational problem, it is not realistic to expect others to do a full, independent replication. And if you can't reproduce the original results, you need access to the original code anyway, to find the source of the differences.