This is crazy. I'm pretty floored that someone did something like this.

Then again, we've all seen (or worse, have been roped into trying to convert!) some of the crazy Excel monstrosities some manager wrote that runs an entire company or such!

Prior to seeing this, I had found (somewhere - dunno if it still exists out there) a "tutorial" on how a neural network works - and the whole thing was done as an Excel worksheet. I thought that was pretty insane at the time...