aparler/RosettaCodeData
1
0
Fork 0
Code Issues 12 Pull requests 3 Projects Releases Packages Wiki Activity Actions

Just another update

Browse source
This commit is contained in:
Ingy döt Net 2015-02-20 00:35:01 -05:00
parent a25938f123
commit 00a190b0a6
6591 changed files with 94363 additions and 23227 deletions
Download patch file Download diff file Expand all files Collapse all files

11
Task/Gamma-function/Perl/gamma-function.pl
View file

@ -3,6 +3,10 @@ use warnings;
use constant pi => 4*atan2(1, 1);
use constant e => exp(1);
# Normally would be: use Math::MPFR
# but this will use it if it's installed and ignore otherwise
my $have_MPFR = eval { require Math::MPFR; Math::MPFR->import(); 1; };
sub Gamma {
my $z = shift;
my $method = shift // 'lanczos';
@ -51,10 +55,15 @@ sub Gamma {
no warnings qw(recursion);
$z < 100 ? Gamma($z + 1, $method)/$z :
sqrt(2*pi*$z)*($z/e + 1/(12*e*$z))**$z / $z;
} elsif ($method eq 'MPFR') {
my $result = Math::MPFR->new();
Math::MPFR::Rmpfr_gamma($result, Math::MPFR->new($z), 0);
$result;
} else { die "unknown method '$method'" }
}
for my $method (qw(lanczos taylor stirling)) {
for my $method (qw(MPFR lanczos taylor stirling)) {
next if $method eq 'MPFR' && !$have_MPFR;
printf "%10s: ", $method;
print join(' ', map { sprintf "%.12f", Gamma($_/3, $method) } 1 .. 10);
print "\n";