> If the new code caused the old code to produce different outputs for the new result, it would show somewhere. At least it did when I was doing computational a

> If the new code caused the old code to produce different outputs for the new result, it would show somewhere. At least it did when I was doing computational astrophysics in academia. For libraries others use, sure. For mere code bases that stay in one professor's team and have been there for 20+ years - not really. As an example, I know one computational group where it often took several hours (possibly days) to generate a single data point in the curve they were trying to produce. None of that team's grad students was willing to waste computational resources to see if their code changes would break prior data points.