I've been tasked with comparing our SW to an independently developed set of SW based on the same requirements. Our systems engineering team build the independent SW and has been using it to model and predict system behaviour.
Currently I'm held up, again, because differences between the two. Yesterday afternoon I identified 5 bugs in the SE version which I'm waiting for them to fix and assess how much that alters their model and prediction of how things should work. This is only the latest batch of bugs I've found in their stuff.
The whole point was to eliminate bug in our production SW, but so far none have been found. I'm up to nearly a dozen bugs in the SE version.