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URL : | http://www.johndcook.com/blog/ | |
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Filed Under: | Academics | |

Posts on Regator: | 1016 | |

Posts / Week: | 5.3 | |

Archived Since: | April 26, 2011 |

This week’s resource post: some pages of notes on special functions: Diagram of relations between special functions Identities for gamma and related functions Relations between Bessel functions Bessel functions in SciPy Gamma and related functions in SciPy See also blog posts tagged special functions. Show More Summary

A string of bits is called primitive if it is not the repetition of several copies of a smaller string of bits. For example, the 101101 is not primitive because it can be broken down into two copies of the string 101. In Python notation, you could produce 101101 by "101"2. The string 11001101, on […]

Ever wonder what the rules were for when to use thou, thee, ye, or you in Shakespeare or the King James Bible? For example, the inscription on front of the Main Building at The University of Texas says Ye shall know the truth and the truth shall make you free. Why ye at the beginning […]

This week’s resource post: some notes on typesetting, Unicode, etc. Common Math Symbols in HTML, XML, TeX, and Unicode Accented letters in HTML, TeX, and Microsoft Word Greek letters in HTML, XML, TeX, and Unicode Unicode resources See also blog posts tagged LaTeX, HTML, and Unicode and the Twitter account TeXtip. Last week: C++ resources […]

I’ve taken the posts from my defunct Symbolism blog and combined them into a couple pages on this site, one for mathematical symbols and other for all other symbols.

Unicode often counts the same symbol (glyph) as two or more different characters. For example, ? is U+03A9 when it represents the Greek letter omega and U+2126 when it represents Ohms, the unit of electrical resistance. Similarly, M is U+004D when it’s used as a Latin letter but U+216F when it’s used as the Roman […]

This week’s resource post: C++ IEEE floating-point exceptions in C++ Unraveling Strings in Visual C++ C++ TR1 regular expressions Random number generation in C++ See also posts tagged C++ Last week: R resources Next week: HTML, TeX, and Unicode

I’ve been going through my old blog posts and fixing a few problems. I found a few missing images, code samples that had lost their indentation, etc. Most of the errors have been my fault, but some were due to bugs in plug-ins. If you see any problems with a post, please let me know. […]

This is the third in my weekly series of posts pointing out resources on this site. This week’s topic is R. R language for programmers Distributions in R Moving data between R and Excel via the clipboard Sweave: First steps toward reproducible analyses Troubleshooting Sweave Regular expressions in R See also posts tagged Rstats. I […]

You can’t subtract 4 from 3 (and stay inside the natural numbers, but you can inside the integers). You can’t divide 3 by 4 (inside the ring of integers, but you can inside the rational numbers). You can’t take the square root of a negative number (in the real numbers, but in the complex numbers […]

For the next few weeks, I’ve scheduled @ProbFact tweets to come out at random times. They will follow a Poisson distribution with an average of two per day. (Times are truncated to multiples of 5 minutes because my scheduling software requires that.)

When I was a postoc I asked a statistician a few questions and he gave me an overview of his subject. (My area was PDEs; I knew nothing about statistics.) I remember two things that he said. A big part of being a statistician is knowing what to do when your assumptions aren’t met, because […]

Suppose you’ve seen a coin come up heads 10 times in a row. What do you believe is likely to happen next? Three common responses: Heads Tails Equal probability of heads or tails. Each is reasonable in its own context. The last answer is correct assuming the flips are independent and heads and tails are […]

This is the second in my series of posts pointing out resources on my site. This week’s topic is Emacs. Emacs kill (cut) commands Emacs point (cursor) movement Getting started with Emacs on Windows Notes on Unicode in Emacs See also the Twitter account UnixToolTip and blog posts tagged Emacs. Last week: Miscellaneous math notes […]

How would you create a table of trig functions without calculators or calculus? It’s not too hard to create a table of sines at multiples of 3°. You can use the sum-angle formula for sines sin(?+?) = sin ? cos ? + sin ? cos ?. to bootstrap your way from known values to other […]

Roughly speaking, an ergodic system is one that mixes well. You get the same result whether you average its values over time or over space. This morning I ran across the etymology of the word: In the late 1800s, the physicist Ludwig Boltzmann needed a word to express the idea that if you took an […]

This web site started as static HTML files. Later I added a WordPress blog, but still wrote some things as static HTML pages for various reasons. Now I’ve moved most of those static pages to WordPress pages so that they’ll have the same style as the blog. There’s not a good way to find these […]

Numericon gives the history of the words googol and googolplex: … the famous googol, 10100 (a 1 followed by 100 zeros), defined in 1929 by American mathematician Edward Kasner and named by his nine-year-old nephew, Milton Sirotta. Milton went even further and came up with the googolplex, now defined as 10googol but initially defined by […]

Princeton University Press and No Starch Press both sent me a couple books this week. Here are a few brief words about each. The first from Princeton was The Best Writing on Mathematics 2014. My favorite chapters were The Beauty of Bounded Gaps by Jordan Ellenberg and The Lesson of Grace in Teaching by Francis Su. […]

Here’s my new business card. Front: Back: Designed by my friend Scott Bronstad. Scott also designed the new look of the web site. (If something doesn’t look quite right, that’s probably my doing.)

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