@futurebird Before I read down the thread I didn’t know what ‘the derivitive’ even related to My father was an engineer, and obnoxious about Being Right, so I went into visual art where the criticism couldn’t follow.

After he died I went back to school for Comp Sci and had to study up to place out of the intro math class — I like math now, but have still never taken a class more advanced than Algebra II (back in 1977 that was)