to your HTML Add class="sortable" to any table you'd like to make sortable Click on the headers to sort Thanks to many, many people for contributions and suggestions. Licenced as X11: http://www.kryogenix.org/code/browser/licence.html This basically means: do what you want with it. */ var stIsIE = /*@cc_on!@*/false; sorttable = { init: function() { // quit if this function has already been called if (arguments.callee.done) return; // flag this function so we don't do the same thing twice arguments.callee.done = true; // kill the timer if (_timer) clearInterval(_timer); if (!document.createElement || !document.getElementsByTagName) return; sorttable.DATE_RE = /^(\d\d?)[\/\.-](\d\d?)[\/\.-]((\d\d)?\d\d)$/; forEach(document.getElementsByTagName('table'), function(table) { if (table.className.search(/\bsortable\b/) != -1) { sorttable.makeSortable(table); } }); }, makeSortable: function(table) { if (table.getElementsByTagName('thead').length == 0) { // table doesn't have a tHead. Since it should have, create one and // put the first table row in it. the = document.createElement('thead'); the.appendChild(table.rows[0]); table.insertBefore(the,table.firstChild); } // Safari doesn't support table.tHead, sigh if (table.tHead == null) table.tHead = table.getElementsByTagName('thead')[0]; if (table.tHead.rows.length != 1) return; // can't cope with two header rows // Sorttable v1 put rows with a class of "sortbottom" at the bottom (as // "total" rows, for example). This is B&R, since what you're supposed // to do is put them in a tfoot. So, if there are sortbottom rows, // for backwards compatibility, move them to tfoot (creating it if needed). sortbottomrows = []; for (var i=0; i
If you wanted to lay tiles on a flat surface, but never have their basic geometric pattern repeat, could you do it? If you could, is there a single uniform tile geometry you could use?
The first question's answer of "yes" has been known for some time, but finding the answer to the second question has perplexed mathematicians for decades. Its answer has only just become understood after decades of research. Veritasium describes the progress they made in whittling down the number of differently shaped tiles you would need to do the job from 20,426, to 96, to 6, then 2, which was the state of the art until 2023.
That brings us to now, as the shape of what might be called "an aperiodic monotile" capable of completely filling a planar surface using a single uniformly shaped tile with no gaps has gotten closer to reality thanks to the work of David Smith, Joseph Samuel Myers, Craig S. Kaplan, and Chaim Goodman-Strauss. The following illustration from their preprint paper shows the basic 13-sided "hat-shaped" polykite tile geometry they've identified:
The hexagonal pattern underlying the basic polykite shape helps explain why this particular geometry can succeed in tiling a plane into infinity, but their solution is not limited to this particular geometry. The following video shows how it can be morphed into other viable variations.
If you look closely at the pattern however, you'll see a number of these tiles represent a "mirrored" or "reflected" variation of the basic polykite geometry. On Twitter, Robert Fathauer took a creative approach to illustrating that property:
The new aperiodic monotile discovered by Dave Smith, Joseph Myers, Craig Kaplan, and Chaim Goodman-Strauss, rendered as shirts and hats. The hat tiles are mirrored relative to the shirt tiles. pic.twitter.com/BwuLUPVT5a
— Robert Fathauer (@RobFathauerArt) March 21, 2023
That small difference raises the challenge of whether a two-dimensional plane could be fully covered with a non-reflected single geometric tile, which has become the final frontier for fully resolving the mathematical challenge.
Given the relative simplicity of the newly defined geometry, the first applications to take advantage of the discovery will almost certainly artistic in nature, which already includes its fast incorporation in video games like HyperRogue. Beyond that, aperiodic tilings involving multiple tile geometries have applications in materials science, where they help understand a unique class of materials called quasicrystals.
Building on that base, aperiodic tiling patterns are also being investigated for application in lightweight structures that are subjected to high vibration environments. For example, the new 13-sided aperiodic monotile would be a candidate to replace traditional isogrid-based geometry in machined structures on aerospace vehicles.
Welcome to the blogosphere's toolchest! Here, unlike other blogs dedicated to analyzing current events, we create easy-to-use, simple tools to do the math related to them so you can get in on the action too! If you would like to learn more about these tools, or if you would like to contribute ideas to develop for this blog, please e-mail us at:
ironman at politicalcalculations
Thanks in advance!
Closing values for previous trading day.
This site is primarily powered by:
The tools on this site are built using JavaScript. If you would like to learn more, one of the best free resources on the web is available at W3Schools.com.