brainwagon

This metafilter post has a link to several interesting recreational and math puzzle books available as downloads. Very cool. The Mathemagician and Pied Puzzler, and others | MetaFilter.

I was reading Nahin’s Digital Dice, which I bought a while ago but which I didn’t really dive into deeply, and he had a nice exposition of Parrondo’s Paradox, which is very neat. Here’s the idea: We are going to play two different coin tossing games. In each case, if we win, we gain one […]

Well, pseudo-random, but reportedly cryptographically strong. 01110 10011 01100 01000 11101 11001 11010 10011 00000 10011 11111 11001 10101 11100 10011 10110 01010 01100 01000 00010 11110 01100 11010 11000 00011 11111 10001 00111 01011 00101 00011 00111 01000 11111 10011 01001 10000 10101 10001 01011 11111 00100 11010 10000 00110 11111 10111 11011 00011 […]

IN

As I was “StumbleUpon”-ing tonight, I was reminded of something that I was thinking about a couple of days ago, and though I’d write it down here. Let’s say we want to multiply, oh… 47 by 69. We begin by writing the two numbers: 47 69 and then proceed by halving the first number and […]

I’ve blogged about D. H. Lehmer’s factoring machines before. It’s fairly hard to convince those who aren’t pathologically interested in rather quirky bits of mathematics and computing that this collection of bicycle chains and sprockets is worthy of study, but I didn’t have much difficulty convincing my typical lunchtime companion Tom that they were interesting, […]

On Friday, I left YAFU factoring a 100 digit number. I returned to find that it had discovered: 57790 93002 97410 10009 81807 59480 96292 62385 64081 79034 01512 68667 60949 55202 41611 02063 00992 86747 29621 36069 = 85404 41503 10330 70274 85067 33621 20528 36393 71759 33321 * 67667 37996 94567 83271 38746 […]

While reading the section on factorization of large numbers in Knuth’s Seminumerical Algorithms, I encountered a reference to an interesting claim by William Stanley Jevons. I did a google search, and found it in google books: Knuth was quick to point out that the number that he gave was easily factorable in short order (even […]

Sometimes, your interests converge. Over on Programming Praxis, he had a coding challenge to implement Monte Carlo factorization. The last couple of days, I have been thinking a bit more about factorization, so it seemed like a good idea to give it a whack. I cribbed a version of the Rabin Miller primality tester off […]

Here’s a nice little math essay regarding big numbers. It ties in interesting notions from computability that are what I think about when I feel more abstract and less practical. Enjoy it with your morning coffee, as I am. Who Can Name the Bigger Number?

Very, very geeky. Q: What’s an anagram of ‘Banach-Tarski’? A: ‘Banach-Tarski Banach-Tarski’. Don’t get it? This might help. Or, it might not.

I’ve been using StumbleUpon to find new webpages on a variety of subjects when I am bored, and as you might have seen from other blog postings (although not so many recently), mathematics is one of those things that I actually find kind of interesting to think about. While scanning around this morning, I found […]

Suppose you wanted to format a nifty math equation for insertion into plain old ordinary email, or maybe as a comment in your C program. For instance, something reasonably complex like this rendition of the series used in the BBP algorithm to compute hexidecimal digits of pi: oo ===== __ \ / 4 2 1 […]

Last year, I wrote a post about a program I wrote to compute a really large prime number. . At the time, 232482657-1 was “king” of the primes, having over 9.8 million digits. Today, one year later, it turns out that the Great Internet Mersenne Prime Search has discovered two even larger primes. I dusted […]

Hmmm. While searching for some unrelated program, I uncovered a program that I wrote which found the following identities: 13 + 123 = 93 + 103 23 + 893 = 413 + 863 83 + 533 = 293 + 503 93 + 343 = 163 + 333 93 + 583 = 223 + 573 103 […]