Joerg asked << Is there anyone on this planet who understands wfl-hilbert ? >> Well, I THINK I managed to figure out how it worked again, last time I tried to read my own documentation and realised the latter required extensive further clarification (supplied) ... But an earlier algorithm (jump_TOPDOWN), later discarded because it could not be inverted, has defied every subsequent attempt to decipher it. Incidentally, 5 years ago several people opined that Hilbert in hyperspace was straightforward. One other (Steve Witham) eventually managed to craft a testable solution, by which time his estimation of its difficulty had been substantially revised. Certainly it is one of the knottier algorithmic design problems I have ever been sufficiently fortunate to solve. Fred Lunnon On 11/15/13, Joerg Arndt <arndt@jjj.de> wrote:
* Fred Lunnon <fred.lunnon@gmail.com> [Nov 15. 2013 18:28]:
On 11/14/13, Warren D Smith <warren.wds@gmail.com> wrote:
... The goal is good hilbert code that fits on 1 page or less. It is desirable to have inverse routine too, i.e. inputs D coordinates and outputs t.
There was extensive discussion of Hilbert walks in hyperspace on math-fun during Sep-Oct 2008, including contributions from Joerg Arndt, Steve Witham, Thomas Colthurst, and myself. The outcome was an efficient algorithm based on D0L systems, implemented in Maple and Java (by WFL) and translated to C (by JJA --- see his fxtbook?).
Sadly not in the fxtbook!
But see http://jjj.de/fxt/demo/comb/index.html#wfl-hilbert
(older routines are http://jjj.de/fxt/demo/comb/index.html#hilbert-ndim and http://jjj.de/fxt/demo/comb/index.html#hilbert-ndim-rec and http://jjj.de/fxt/demo/comb/index.html#stringsubst-hilbert3d )
Is there anyone on this planet who understands wfl-hilbert ?
[...]
@WDS: easy Peano mappings exist for all odd side-lengths of hypercubes.
Best, jj
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