Hi.
I was playing around and made this stair depth/height ergonomics calculator. It is based on the rules laid out by the French mathematician, engineer and architect Nicolas-Francois in his book Cours d’architecture from 1683, and is the basis of the ISO-norms of today. It is not a full blown stair calculator, and, disclaimer, it requires metahopper to work:
Blondel Stair Rules.gh (47.9 KB)
Perhaps @martinsiegrist will enjoy this, or @laurent_delrieu, because math and French.
Here is the image for the Image Sampler:
even if it is only visual sugar.
Clearly, no one who liked my thread openend up the script and played around with it or I would have been notified by now that the tread and riser values were being pulled to the rule regions instead of being bounded by them 
:
I fixed this:
Blondel Stair Rules VR 02.gh (75.9 KB)
and also added an inch or centimeter selector instead of simply calculating with centimeters and providing a converted inch output.