Message #1441

From: Andrey <>
Subject: Re: [MC4D] Social dream
Date: Tue, 22 Feb 2011 16:24:28 -0000

Roice, thank you.
About angles: I suggest to keep them in the way where angle doesn’t depend on the puzzle. So that when you see the rotation angle value in the log file, you can find its value in degrees without knowing of the puzzle body.
For example, compare hyperboxes 4^4 and 3x3x4x4. If we have two axes (1,0,0,0) and (0,0,1,0) then 4^4 allows 90-deg twists in this direction, and for 3x3x4x4 only 180-deg twists are possible. In my notation 180-deg twists for these two puzzles will have the same angle=6 (12/2).
Another example is something like alternated douprism [2n]x[2k] (it is not included in uniform polychora list because some of its cells are non-regular tetrahedra). Rotation of its main cell (antiprism?) is possible only to 360/n degrees. In the douprism [2n]x[2k] (with the same set of axes) rotations to 360/2n degrees are possible.
Also different programs may have different ideas about minimal rotation angle for some pair of axes in the set. If these values will be different than there is more chance that programs will not understand each other’s log.
Something like that.


— In, Roice Nelson <roice3@…> wrote:
> I very much like what Andrey specified for the twist definition in future
> log files.
> The only thing I questioned while reading was whether it is necessary to
> store the rotation angles in such a way that they depend on the puzzle. So
> rather than storing 12/3=4 for a 120 degree rotation on the simplex, why not
> simply store 3? This would make those values more readable across puzzles,
> since any order-3 rotation would be saved the same. Maybe I am missing
> another need there though.
> Roice