The app on your Mac today isn't a rewrite of the legendary Mac OS 7.2.1 Graphing Calculator, but an acquired app based on Curvus Pro introduced in OSX Tiger.
The first one has a legendary backstory.
2 devs snuck into Apple after their project was canceled:
https://www.pacifict.com/Story/
This highlights what I think is missing within a lot of tech companies today. I don’t know too many people who are so passionate about what they’re doing that they would sneak into their former employer’s office buildings and then find employees willing to work together with them to finish a project that simply had to get done. That alone makes me a bit sad.
“We looked at each other, took a deep breath, and launched the application. The monitor burst into flames. We calmly carried it outside to avoid setting off smoke detectors, plugged in another monitor, and tried again.”
Grapher.app is different from Graphing Calculator. It came via an acquisition. All the details are here if you want to read the backstory (assuming the info is correct: https://en.wikipedia.org/wiki/Grapher)
The first one has a legendary backstory. 2 devs snuck into Apple after their project was canceled: https://www.pacifict.com/Story/
Curvus Pro: https://macintoshgarden.org/apps/curvus-pro