{"id":19801,"date":"2018-04-09T22:48:09","date_gmt":"2018-04-10T03:48:09","guid":{"rendered":"http:\/\/blog.kenperlin.com\/?p=19801"},"modified":"2018-04-09T22:50:08","modified_gmt":"2018-04-10T03:50:08","slug":"math-with-my-brother-part-6","status":"publish","type":"post","link":"https:\/\/blog.kenperlin.com\/?p=19801","title":{"rendered":"Math with my brother, part 6"},"content":{"rendered":"<p>Let&#8217;s review. We&#8217;re looking for a way to find a regular simplex &#8212; the simplest symmetric shape with flat boundaries &#8212; and we want our method to work no matter how many dimensions it has.<\/p>\n<p>We already saw that to get a one dimensional simplex &#8212; a line &#8212; you go up to two dimensions and draw a line between the two points (1,0) and (0,1), keeping only the parts where all the coordinates are positive.<\/p>\n<p>To get a two dimensional simplex &#8212; an equilateral triangle &#8212; you go up to three dimensions and draw a plane between the three points (1,0,0), (0,1,0) and (0,0,1), keeping only the parts where all the coordinates are positive.<\/p>\n<p>It turns out this trick works in <i>any<\/i> number of dimensions.  For example, suppose we want to get the three dimensional simplex &#8212; a regular tetrahedron.<\/p>\n<p>You go up to four dimensions and draw a volume between the four points (1,0,0,0), (0,1,0,0), (0,0,1,0) and (0,0,0,1), keeping only the parts where all the coordinates are positive. In this picture, the x,y,z,w axes &#8212; all at right angles to each other &#8212; are in blue, and the resulting simplex is bounded by thick black lines:<\/p>\n<p><center><img decoding=\"async\" src=\"http:\/\/blog.kenperlin.com\/wp-content\/uploads\/2018\/04\/simplex3_m.png\" width=225><\/center><\/p>\n<p>Wait, what was that?  Draw a <i>volume<\/i>???<\/p>\n<p>Well, sure. Math doesn&#8217;t care how many dimensions you have. It doesn&#8217;t even care whether you can picture in your head the thing you&#8217;re talking about. It just does exactly what you tell it to.<\/p>\n<p>And now, thanks to the statistically inspired math my brother showed me, I have a way to create a regular simplex in <i>any<\/i> number of dimensions &#8212; even a hundred dimensions, or a million. It may not make any visual sense to me, but I can describe it exactly.<\/p>\n<p>And when you think about it, that&#8217;s pretty cool.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Let&#8217;s review. We&#8217;re looking for a way to find a regular simplex &#8212; the simplest symmetric shape with flat boundaries &#8212; and we want our method to work no matter how many dimensions it has. We already saw that to get a one dimensional simplex &#8212; a line &#8212; you go up to two dimensions &hellip; <a href=\"https:\/\/blog.kenperlin.com\/?p=19801\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Math with my brother, part 6&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/19801"}],"collection":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=19801"}],"version-history":[{"count":6,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/19801\/revisions"}],"predecessor-version":[{"id":19808,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/19801\/revisions\/19808"}],"wp:attachment":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19801"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19801"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19801"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}