Marshall's Weblog » Math http://www.mickelson.org Embiggen Your Mind Mon, 25 Jul 2011 20:16:11 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Does .9999999… = 1? http://www.mickelson.org/2007/02/19/does-9999999-1/ http://www.mickelson.org/2007/02/19/does-9999999-1/#comments Tue, 20 Feb 2007 00:46:12 +0000 Marshall http://www.mickelson.org/2007/02/19/does-9999999-1/

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]]> Apparently there is a lot of discussion out there as to the validity of this statement. The main argument for equality goes something like this. Say x = 0.99999… (or commonly expressed as .9). Multiply both sides by 10 and you have 2 equations that you can subtract from each other.

 10x = 9.9999999...
-  x = 0.9999999...
-------------------
  9x = 9

Reduce the result and now you have x = 1, but as we expressed earlier, x = 0.99999, so 0.99999… = 1. Simple enough, right?

Check out all of the discussion here, here, and and some false counter-examples here.

]]> http://www.mickelson.org/2007/02/19/does-9999999-1/feed/ 1 Science Links of the Week http://www.mickelson.org/2007/02/17/science-links-of-the-week/ http://www.mickelson.org/2007/02/17/science-links-of-the-week/#comments Sun, 18 Feb 2007 02:44:51 +0000 Marshall http://www.mickelson.org/2007/02/17/science-links-of-the-week/

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]]> Programmable Water – An MIT student creates logic gates that switch with the power of water.

NetLogo – A programmable modeling environment

Earth’s Hum – Earth’s Hum is explained by scientists as being caused by waves in the oceans. If you haven’t heard Earth’s hum, well, that is because you can’t. Only the most sensitive seismometers can detect them.

Science vs. Faith

The Multiverse – Parallel Universes as explained by Professor Max Tegmark of MIT.

]]> http://www.mickelson.org/2007/02/17/science-links-of-the-week/feed/ 0 Strange Math… http://www.mickelson.org/2007/01/09/strange-math/ http://www.mickelson.org/2007/01/09/strange-math/#comments Wed, 10 Jan 2007 03:01:02 +0000 Marshall http://www.mickelson.org/2007/01/09/strange-math/ Apple Inc. + Google + Yahoo + Cingular = iPhone!

iPhone

I know I will be buying one in June when they come out.

]]> http://www.mickelson.org/2007/01/09/strange-math/feed/ 0 Four Fours http://www.mickelson.org/2006/12/06/four-fours/ http://www.mickelson.org/2006/12/06/four-fours/#comments Thu, 07 Dec 2006 03:21:58 +0000 Marshall http://www.mickelson.org/2006/12/06/four-fours/

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]]> I just found out about a little math game called Four Fours. Basically what you try to do is try to represent integers using only the number 4 and a few common mathematical operators, for example:

0 = 4 – 4 + 4 – 4
1 = ( 4 + 4 ) / ( 4 + 4 )
2 = ( 4 * 4 ) / ( 4 + 4 )
…

There are also solvers out there in C# and also in Python.

]]> http://www.mickelson.org/2006/12/06/four-fours/feed/ 3 The Math behind Google’s PageRank http://www.mickelson.org/2006/12/06/the-math-behind-googles-pagerank/ http://www.mickelson.org/2006/12/06/the-math-behind-googles-pagerank/#comments Thu, 07 Dec 2006 02:47:31 +0000 Marshall http://www.mickelson.org/2006/12/06/the-math-behind-googles-pagerank/ The American Mathematical Society has a fairly indepth article on how Google computes the PageRank.

]]> http://www.mickelson.org/2006/12/06/the-math-behind-googles-pagerank/feed/ 0 Need the Inverse Square Root of a Number, Fast? http://www.mickelson.org/2006/12/01/need-the-inverse-square-root-of-a-number-fast/ http://www.mickelson.org/2006/12/01/need-the-inverse-square-root-of-a-number-fast/#comments Sat, 02 Dec 2006 05:10:14 +0000 Marshall http://www.mickelson.org/2006/12/01/need-the-inverse-square-root-of-a-number-fast/ > 1); is the most curious part of the function, and apparently is has to do with (…)

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]]> Quake 3 has a the following bit of code to calculate the inverse square of an integer.

InvSqrt()

The i = 0x5f3759df - (i >> 1); is the most curious part of the function, and apparently is has to do with Newton’s Method, which is an efficient way to approximate the roots of a function.

( via Slashdot )

]]> http://www.mickelson.org/2006/12/01/need-the-inverse-square-root-of-a-number-fast/feed/ 0 Math is Delicious! http://www.mickelson.org/2006/09/18/math-is-delicious/ http://www.mickelson.org/2006/09/18/math-is-delicious/#comments Tue, 19 Sep 2006 03:04:17 +0000 Marshall http://www.mickelson.org/2006/09/18/math-is-delicious/ I found another funny web comic, Questionable Content, which reminds us that Math is Delicious!

]]> http://www.mickelson.org/2006/09/18/math-is-delicious/feed/ 0 A New Form of Cryptography http://www.mickelson.org/2006/09/14/a-new-form-of-cryptography/ http://www.mickelson.org/2006/09/14/a-new-form-of-cryptography/#comments Fri, 15 Sep 2006 03:14:26 +0000 Marshall http://www.mickelson.org/2006/09/14/a-new-form-of-cryptography/

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]]> Today I found another really neat webcomic: xkcd.com. I for one am really excited about the new miss-elliot algorithm. Today‘s strip, Commented, took me a few seconds to get. (Hint: Just think of a C++ or C# IDE)

Other comics I visit regularly:

What, if anything, do you all read?

]]> http://www.mickelson.org/2006/09/14/a-new-form-of-cryptography/feed/ 0 A Proof That the Rich do Little Work http://www.mickelson.org/2006/04/16/a-proof-that-the-rich-do-little-work/ http://www.mickelson.org/2006/04/16/a-proof-that-the-rich-do-little-work/#comments Sun, 16 Apr 2006 23:59:56 +0000 Marshall http://www.mickelson.org/2006/04/16/a-proof-that-the-rich-do-little-work/ You can’t argue with mathematics!

]]> http://www.mickelson.org/2006/04/16/a-proof-that-the-rich-do-little-work/feed/ 0 Solving Sudoku with SQL http://www.mickelson.org/2006/03/30/solving-sudoku-with-sql/ http://www.mickelson.org/2006/03/30/solving-sudoku-with-sql/#comments Fri, 31 Mar 2006 03:53:32 +0000 Marshall http://www.mickelson.org/2006/03/30/solving-sudoku-with-sql/ I guess SQL can be used to solve all lifes problems. What is next, a Whitespace Sudoku solver?

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