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Factors of a Mersenne number: Difference between revisions

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Factors of a Mersenne number (view source)

Revision as of 10:56, 1 May 2021

527 bytes removed ,  3 years ago
m
→‎{{header|Raku}}: modernize a bit, use built-ins
m (→‎{{header|Raku}}: modernize a bit, use built-ins)
Line 2,493:
=={{header|Raku}}==
(formerly Perl 6)
{{Works with|rakudo|2015.12}}
<lang perl6>my @primes = 2, 3, -> $n is copy {
repeat { $n += 2 } until $n %% none do for @primes -> $p {
last if $p > sqrt($n);
$p;
}
$n;
} ... *;
multi factors(1) { 1 }
multi factors(Int $remainder is copy) {
gather for @primes -> $factor {
if $factor * $factor > $remainder {
take $remainder if $remainder > 1;
last;
}
while $remainder %% $factor {
take $factor;
last if ($remainder div= $factor) === 1;
}
}
}
 
sub is_prime($x) { (state %){$x} //= factors($x) == 1 }
 
<lang perl6>sub mtest($bits, $p) {
my @bits = $bits.base(2).comb;
loop (my $sq = 1; @bits; $sq %= $p) {
$sq *×= $sq;
$sq += $sq if 1 == @bits.shift;
}
$sq == 1;
Line 2,528 ⟶ 2,504:
 
for flat 2 .. 60, 929 -> $m {
next unless is_primeis-prime($m);
my $f = 0;
my $x = 2**$m - 1;
my $q;
for 1..* -> $k {
$q = 2 *× $k *× $m + 1;
next unless $q % 8 == 1|7 or is_primeis-prime($q);
last if $q *× $q > $x or $f = mtest($m, $q);
}
 
Thundergnat
10,327

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