Comments on: Project Euler and Calc Mode http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/ Leveraging Perl and Emacs Tue, 07 May 2013 11:25:25 +0000 hourly 1 http://wordpress.com/ By: Interesting Emacs Links - 2009 Week 9 « A Curious Programmer http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/#comment-7302 Sun, 01 Mar 2009 17:56:43 +0000 http://curiousprogrammer.wordpress.com/?p=256#comment-7302 [...] others, I should also point out my own posts on solving mathematical problems using calc mode and on mapping aliases to dired [...]

]]> By: Jared http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/#comment-7279 Sun, 22 Feb 2009 18:05:58 +0000 http://curiousprogrammer.wordpress.com/?p=256#comment-7279 Hi Rider,

I’d be interested to see that research, but I guess the story isn’t _too_ incredible.

]]> By: Rider of Giraffes http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/#comment-7277 Sun, 22 Feb 2009 10:19:20 +0000 http://curiousprogrammer.wordpress.com/?p=256#comment-7277 Research suggests that Mel was real, and that the incidents recounted did actually happen.

]]> By: Jared http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/#comment-7276 Sat, 21 Feb 2009 21:55:48 +0000 http://curiousprogrammer.wordpress.com/?p=256#comment-7276 Ah yes, I know about that one, and also max-specpdl-size that is also often required at the same time. I probably didn’t know about it when I was trying to solve problem 26 though.

Thanks.

(let ((max-lisp-eval-depth 10000)
(max-specpdl-size 10000))
(length (primes 1 10000)))

]]> By: phayes http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/#comment-7275 Sat, 21 Feb 2009 19:29:36 +0000 http://curiousprogrammer.wordpress.com/?p=256#comment-7275 Hi Jared,

(let ((max-lisp-eval-depth 1000)) (primes 2 997))
:)

]]> By: Jared http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/#comment-7274 Sat, 21 Feb 2009 17:02:09 +0000 http://curiousprogrammer.wordpress.com/?p=256#comment-7274 Hi Phayes,

No, it wouldn’t have found it if the answer hadn’t been in that range. However, I originally ran it on all the numbers (not just prime) between 2 and 999. It took a few seconds to run and determined the correct result. It wasn’t really necessary to restrict the search to just primes.

I actually solved the problem a few months ago so I forget why I chose a range of 900 to 1000. Could it be because recursion is extremely limited in emacs and it was unable to generate primes from 2 to 999?

]]> By: phayes http://curiousprogrammer.wordpress.com/2009/02/21/project-euler-and-calc-mode/#comment-7273 Sat, 21 Feb 2009 11:43:08 +0000 http://curiousprogrammer.wordpress.com/?p=256#comment-7273 Did you only try the primes between 900 and 1000? I notice the largest prime d < 1000 which generates a d-1 length cyclic (is a full reptend prime) is the 166th prime, 983 – so it must be the right answer – but not all primes do so. All you can say of any prime d is that the length of its reciprocal decimal digit cycle divides d-1. Would your program have been certain to find the right answer if there had been no full reptend primes in that interval?

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