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
Tired of trigonometry? Having trouble keeping track of all those sines, cosines, tangents, cotangents, et cetera, so on and so forth?
Norman Wildberger of the University of New South Wales in Sydney, Australia may have done away with all of those in rewriting the Euclidean geometry that we've all come to know and dread in high school math classes. Here's the scoop from the UNSW's news release announcing the publication of his book Divine Proportions: Rational Trigonometry to Universal Geometry, now available from Wild Egg Books:
This text introduces a new and simplified approach to trigonometry and a major restructuring of Euclidean geometry. It replaces cos, sin, tan and all those other transcendental trig functions with rational functions and elementary arithmetic. It develops a complete theory of planar Euclidean geometry over a general field without any reliance on 'axioms'. And it shows how to apply this new theory to a wide range of practical problems from engineering, physics, surveying and calculus.
The news release spells out the potential impact for math students:
Trigonometry has for centuries been difficult for students to learn. Part of the reason is that the foundations of the subject are problematic, relying on vague pictorial definitions of the key concepts of angles and trigonometric functions. That means students rarely come to grips with the logical structure of the theory. Rational trigonometry is much simpler, relying on the fundamental quadratic notions of quadrance and spread, and with basic laws that can be derived completely rigorously using only elementary algebra.
As it happens, quadrance is equal to the square of the distance between two points and spread is equal to the square of the sine of an angle. Here are some extracts from the text that provide more detail of the scope of Wildberger's rewriting of the rules of trigonometry:
Sigh. Where was this guy when I was in school....
Labels: math
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