Whoa! At the suggestion of a little bird, I simply said CloudPublish[] in that Lab notebook, and it returned the URL https://www.open.wolframcloud.com/objects/289beb45-8914-44d6-bc9e-8a869c73fc... Please see if you can access it! —rwg (Not so lucky ("Unknown error") trying to publish the 92 Johnsons from my laptop.) On Tue, Feb 26, 2019 at 5:41 AM Bill Gosper <billgosper@gmail.com> wrote:
A nice little three-liner: http://gosper.org/johnson7.pdf . Is it convex? This pdf is a spoiler for a programming lab (https://lab.open.wolframcloud.com/app/) notebook because I have yet to figure out how to unrestrict public access. But wouldn't it be a great way for math-funsters to share typesetting, images, animations, and interactions?
If not convex, exactly what is that nearly straight angle? Note that evil (and misnamed) FindGeometricTransform coerces to floating point!
[Mathematica developers: Needs Exact->True option. MachinePrecision isn't quite sufficient
for RootApproximant to reconstruct the algebraics here. A consolation would be WorkingPrecision.]
]
I think at some point I exhaustively searched PolyhedronData for Johnson glue jobs and found even narrower convexity failures. Johnson was working with cardboard? —rwg I need to tweak gosper.org/johnsonposter.pdf to disambiguate some hidden undersides.