http://www.cse.unsw.edu.au/~dons/blog Thoughts on programming en http://www.cse.unsw.edu.au/~dons/blog/2009/01/21#moved After 3.5 years, I've finally given up on my custom blosxom and darcs blog setup, and moved the entire blog to wordpress. Now we get much more automation, and ease of use for me. <a href="http://donsbot.wordpress.com/">Go here.</a> http://www.cse.unsw.edu.au/~dons/blog/2008/09/30#primes <p> Thanks to Ward Harold for the heads up about UCLA's <a href="http://www.guardian.co.uk/science/2008/sep/29/maths">new mersenne prime discovery</a>. </p> <p> With <A href="http://haskell.org">Haskell's</a> default unbounded Integer type, you can have a look at this beast with little effort. Here's the Haskell program to print the prime to stdout: </p> <pre> <span class='varid'>main</span> <span class='keyglyph'>=</span> <span class='varid'>print</span> <span class='layout'>(</span><span class='num'>2</span><span class='varop'>^</span><span class='num'>43112609</span><span class='comment'>-</span><span class='num'>1</span><span class='layout'>)</span> </pre> <p> Compile and run this program: </p> <pre> $ ghc -O2 --make A.hs $ time ./A > /tmp/prime.txt ./A > /tmp/prime.txt 34.14s user 0.23s system 99% cpu 34.462 total </pre> <p> And we get a 13M file containing <a href="http://www.cse.unsw.edu.au/~dons/prime.txt">31647026933025592314 ... 78265780022181166697152511</a>. Enjoy! </p>