diff options
| -rw-r--r-- | challenge-246/mark-anderson/raku/ch-2.raku | 26 |
1 files changed, 6 insertions, 20 deletions
diff --git a/challenge-246/mark-anderson/raku/ch-2.raku b/challenge-246/mark-anderson/raku/ch-2.raku index b411ffd00a..52ef177f92 100644 --- a/challenge-246/mark-anderson/raku/ch-2.raku +++ b/challenge-246/mark-anderson/raku/ch-2.raku @@ -7,27 +7,13 @@ ok linear-recurrence-of-second-order([4,1,2,-3,8]); sub linear-recurrence-of-second-order(@a) { - my @eqn = @a.rotor(3 => -2).head(2); - my $p = p(@eqn).narrow; - my $q = q(@eqn.pop, $p).narrow; + my @eqn = @a.rotor(3 => -2); - return False unless all($p, $q) ~~ Int; + my $p = (.[2] / .[0] given .[0] >>*>> .[1;1] >>-<< .[1] >>*>> .[0;1]).narrow given @eqn; - @a eqv (@a[0], @a[1], -> $a, $b { $a*$p + $b*$q }...*).head(5).Array -} - -sub p(@a) -{ - given @a - { - .[2] / .[0] given .[0] >>*>> .[1;1] >>-<< .[1] >>*>> .[0;1] - } -} + my $q = ((.[2] - .[0]*$p) / .[1]).narrow given @eqn.tail; -sub q(@a, $p) -{ - given @a - { - (.[2] - .[0]*$p) / .[1] - } + return False unless all($p, $q) ~~ Int; + + @a eqv (@a[0], @a[1], { $^a*$p + $^b*$q }...*).head(5).Array } |