Combinations and permutations: Difference between revisions
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Printing of test cases is performed incrementally, which is associated with the characteristics of the device output.
=={{header|Perl}}==
Although perl can handle arbitrarily large numbers using Math::BigInt and Math::BigFloat, it's
native integers and floats are limited to what the computer's native types can handle.
As with the perl6 code, some special handling was done for those values which would have overflowed the native floating point type.
<lang perl>use strict;
use warnings;
showoff( "Permutations", \&P, "P", 1 .. 12 );
showoff( "Combinations", \&C, "C", map $_*10, 1..6 );
showoff( "Permutations", \&P_big, "P", 5, 50, 500, 1000, 5000, 15000 );
showoff( "Combinations", \&C_big, "C", map $_*100, 1..10 );
sub showoff {
my ($text, $code, $fname, @n) = @_;
print "\nA sample of $text from $n[0] to $n[-1]\n";
for my $n ( @n ) {
my $k = int( $n / 3 );
print $n, " $fname $k = ", $code->($n, $k), "\n";
}
}
sub P {
my ($n, $k) = @_;
my $x = 1;
$x *= $_ for $n - $k + 1 .. $n ;
$x;
}
sub P_big {
my ($n, $k) = @_;
my $x = 0;
$x += log($_) for $n - $k + 1 .. $n ;
eshow($x);
}
sub C {
my ($n, $k) = @_;
my $x = 1;
$x *= ($n - $_ + 1) / $_ for 1 .. $k;
$x;
}
sub C_big {
my ($n, $k) = @_;
my $x = 0;
$x += log($n - $_ + 1) - log($_) for 1 .. $k;
exp($x);
}
sub eshow {
my ($x) = @_;
my $e = int( $x / log(10) );
sprintf "%.8Fe%+d", exp($x - $e * log(10)), $e;
}
</lang>
Since the output is almost the same as perl6's, and this is only a Draft RosettaCode task, I'm not going to bother including the output of the program.
=={{header|Perl 6}}==
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