Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
Anonymous Monk,
Ok - this is an adaptation of Challenge: Nearest Palindromic Number. Since the mathematical lesson has already been explained, I decided to spruce up the Perl so that there might be a lesson in it.
#!/usr/bin/perl use strict; use warnings; my $nearest_prime = nearest(); for ( map { int( rand 9998 ) + 2 } 1 .. 50 ) { print "$_ : ", $nearest_prime->( $_ ), "\n"; } sub nearest { my $prime = is_prime(); return sub { my $n = shift; return $n if $prime->( $n ); my $pos = $n; ++$pos while ! $prime->( $pos ); $pos = $pos - $n; my $neg = $n; --$neg while ! $prime->( $neg ); $neg = $n - $neg; return $pos > $neg ? $n - $neg : $n + $pos; } } sub is_prime { my %prime = map { $_ => 1 } (2, 3, 5, 7); my %not_prime; return sub { my $n = shift; return 1 if $prime{ $n }; return 0 if $n % 2 == 0 || exists $not_prime{ $n }; for ( 3 .. sqrt $n ) { return $not_prime{ $n } = 0 if $n % $_ == 0; } return $prime{ $n } = 1; }; }
I will leave converting the code from the nearest prime to the nearest N primes as an exercise for the reader.

Cheers - L~R


In reply to Re: a close prime number by Limbic~Region
in thread a close prime number by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others chanting in the Monastery: (10)
    As of 2014-08-27 09:23 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      The best computer themed movie is:











      Results (235 votes), past polls