Posts

Showing posts from June 3, 2012

Random Math Notes: Friedrich Hirzebruch, Theorema Egregium, … (2012-06-06)

Perm URL with updates: http://xahlee.org/math/random_math_notes_2012-06-08.htmllearned today from my friend Richard Palais that Friedrich Hirzebruch (1927 〜 2012) passed away last week.Friedrich Ernst Peter Hirzebruch (17 October 1927 – 27 May 2012) was a German mathematician, working in the fields of topology, complex manifolds and algebraic geometry, and a leading figure in his generation. He has been described as “the most important mathematician in the Germany of the postwar period.”Complex manifoldsIn differential geometry, a complex manifold is a manifold with an atlas of charts to the open unit disk[1] in Cn, such that the transition maps are holomorphic.The term complex manifold is variously used to mean a complex manifold in the sense above (which can be specified as an integrable complex manifold), and an almost complex manifold.Holomorphic = Holomorphic function. Quote:In mathematics, holomorphic functions are the central objects of study in complex analysis. A holomorphic …

傷心酒店 (Heartbreak Bar)

Image
Perm URL with updates: http://xahlee.org/music/heartbreak_bar.html江蕙+施文彬 - 傷心酒店. 傷心酒店 作詞:羅文聰 作曲:吉幾三 Date: 1993 (女) 冷淡的光線, 哀怨的歌聲, 飲酒的人無心情 (女) 世間的繁華, 好像夢一場, 也是沒有用 (男) 暗淡酒店內, 悲傷誰人知, 痛苦吞腹內 △0 (女) 一杯又再來 (男) 妳若有了解 (合) 甭問我從那來 △1 (女) 不願講出來, 鬱悶在心裡, 感情失落的無奈 (女) 苦苦在等待, 還是等不到愛, 虛情的對待 (男) 多情的世界, 找不到真愛, 引我心悲哀 △2 (女) 有愛也罷 (男) 無愛也快活 (合) 今夜伴我是孤單 (合) 冷淡的光線, 哀怨的歌聲, 飲酒的人無心情 (合) 世間的繁華, 好像夢一場, 也是沒有用 (男) 暗淡酒店內, 悲傷誰人知, 痛苦吞腹內 △0 △1 △2 (男) 多情的世界, 找無真情愛, 引我心悲哀 △2 蔡幸娟+傅振輝 - 傷心酒店Quick translation: Heartbreak Bar cold lights, sad music, this drinker has no mood the beautiful world, a transient dream, useless this dim lit bar, who can understand, i keep to myself drink after drink if you understand don't ask me where i'm from unable to to tell, the sadness in my heart, the feelings of heartbreak waiting for a love, that never came, the uncaring treatment this beautiful world, but no love for me, only the blues 皓皓 - 伤心酒店 (singing both male/female)未識綺羅香 (A Poor Girl)蕭孋珠 - 詩意 (Shiyi)葉蒨文 - 晚风 (Nig…

English Accents

ODE notation considered harmful

Nice article:ODE notation considered harmful2012-06-05 By ?. @ Source stochastix.wordpress.comSee also: The Problems of Traditional Math Notation.

men need to be assholes, women need to be pretty

post removed because it might violate Google's ad program policy. See here instead: 〈Xah's Sex Blog〉 http://xahlee.org/sex/blog.html

Skateboarding Flips in Slow Motion

Image

Gmail State-Sponsored Attack Warning 2012-06-06

Image
I'm getting a warning from Gmail.Gmail state-sponsored attack warning 2012-06-06It started yesterday. I've since turned on Google's 2-steps verification, but the warning still come on today. It's pretty weird, since am in USA, and am not a China activist. Hardly know anyone in China except a few programers recently met on twitter.

Nice Text Column Commands in cua-mode

There's a nice feature of cua-mode. Turn it on, then 【Ctrl+Enter】 to start selecting rectangle. Then, you can start typing to insert text to the whole column, or press 【⌫ Backspace】 to delete to the left every char on the left boundary, or press 【⌦ Delete】 to delete the whole rectangle, or use any of {Cut, 【Ctrl+x】, Copy 【Ctrl+c】, Paste 【Ctrl+v】}. To cancel selection, press 【Ctrl+Enter】 again.This is much better than emacs's rectangular commands (e.g. kill-rectangle 【Ctrl+xrk】) because it visually highlight only the column selection, and no need for use specialized rectangle commands.via +Markus Schützfor more about working with column text, see: Emacs: Manipulate Column Text, string-rectangle, ASCII-Art

emacs url-unhex-string defect

Perm URL with updates: http://xahlee.org/emacs/emacs_bugs.htmlThe emacs functions {url-unhex-string, gnus-url-unhex-string} returns incorrect result. Example: (require 'url-util) ;; emacs-24.1.50_2/lisp/url/url-util.el (url-hexify-string "Gauss–Bonnet_theorem") ; returns "Gauss%E2%80%93Bonnet_theorem" (url-unhex-string "Gauss%E2%80%93Bonnet_theorem") ;; returns "Gauss\342\200\223Bonnet_theorem" (require 'gnus-util) ;; emacs-24.1.50_2/lisp/gnus/gnus-util.el (gnus-url-unhex-string "Gauss%E2%80%93Bonnet_theorem") ;; returns "Gauss–Bonnet_theorem" ;; correct result should be: "Gauss–Bonnet_theorem" Another issue is, why there's duplicate {url-unhex-string, gnus-url-unhex-string}?Some discussion and temp solutions at:gnu.emacs.helpcomp.lang.lispReported to FSF: bug#6252.For browser's behavior, see: URL Percent Encoding and Unicode. For example of correct behavior in JavaScript, see: JavaScript Encode …

math: Fractal Gears

Image
“clockwork” (2012) by zy0rg. img src

CSS 3 Selector not in CSS 2.1

Here's CSS 3 selector syntax that's not in CSS 2.1.PatternMeaning‹tag›[‹attr›^="‹val›"]Matches any ‹tag› element whose ‹attr› attribute value begins with the string "‹val›"‹tag›[‹attr›$="‹val›"]Matches any ‹tag› element whose ‹attr› attribute value ends with the string "‹val›"‹tag›[‹attr›*="‹val›"]Matches any ‹tag› element whose ‹attr› attribute value contains the string "‹val›"PatternMeaning‹tag›:rootMatches element ‹tag› that is root of document.‹tag›:nth-child(‹n›)Matches element ‹tag› that is nth child of its parent.‹tag›:nth-last-child(‹n›)Matches element ‹tag› that is nth child of its parent, counting from the last one.‹tag›:nth-of-type(‹n›)Matches element ‹tag› that is nth child of the same type.‹tag›:nth-last-of-type(‹n›)Same as ‹tag›:nth-of-type(‹n›) but counting from bottom.‹tag›:last-childMatches element ‹tag› when ‹tag› is the last child of its parent.‹tag›:first-of-typeSame as ‹tag›:nth-of-type(1)‹tag›:l…

Emacs 24 Package System Problems

Perm URL with updates: http://xahlee.org/emacs/emacs_package_system_problem.htmlThis page describes some flaws with emacs 24's package system. If you are not familiar what it is, see: A Guide on Emacs 24 Package System.2012-06-02 does anyone have problems with emacs package system?recently, installed several packages with it: {rainbow-mode, “bookmark+”, smex, “expand-region”}.But they all have a similar problem related to autoload. For example, let's say rainbow-mode. When opening a CSS file, it's not loaded. You have to manually call it. So, if you want it to activate in CSS, you have to add stuff to your init file. Then, this means the package system does not really automatically manage things. You still have know some elisp, and manually add things to your init file. (we talking about basic activation, not advanced customization)The issue is more pronounced with modes such as “bookmark+”, smex, “expand-region”. For example, after installing “bookmark+”, restart emacs, th…