38 lines
1.1 KiB
Raku
38 lines
1.1 KiB
Raku
use List::Divvy;
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use Lingua::EN::Numbers;
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sub is-blum(Int $n ) {
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return False if $n.is-prime;
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my $factor = find-factor($n);
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return True if ($factor.is-prime && ( my $div = $n div $factor ).is-prime && ($div != $factor)
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&& ($factor % 4 == 3) && ($div % 4 == 3));
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False;
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}
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sub find-factor ( Int $n, $constant = 1 ) {
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my $x = 2;
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my $rho = 1;
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my $factor = 1;
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while $factor == 1 {
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$rho *= 2;
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my $fixed = $x;
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for ^$rho {
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$x = ( $x * $x + $constant ) % $n;
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$factor = ( $x - $fixed ) gcd $n;
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last if 1 < $factor;
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}
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}
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$factor = find-factor( $n, $constant + 1 ) if $n == $factor;
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$factor;
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}
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my @blum = lazy (2..Inf).hyper(:1000batch).grep: &is-blum;
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say "The first fifty Blum integers:\n" ~
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@blum[^50].batch(10)».fmt("%3d").join: "\n";
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say '';
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printf "The %9s Blum integer: %9s\n", .&ordinal-digit(:c), comma @blum[$_-1] for 26828, 1e5, 2e5, 3e5, 4e5;
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say "\nBreakdown by last digit:";
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printf "%d => %%%7.4f:\n", .key, +.value / 4e3 for sort @blum[^4e5].categorize: {.substr(*-1)}
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