pidigits benchmark and bpi() method in Math::BigFloat/Math::BigInt, take 7 [PATCH]

Message-Id: <200706081929.44888@bloodgate.com>

p4raw-id: //depot/perl@31364

1 files changed, 56 insertions, 8 deletions

diff --git a/lib/Math/BigInt.pm b/lib/Math/BigInt.pm
index f99eea617e..10aeb1b025 100644
--- a/lib/Math/BigInt.pm
+++ b/lib/Math/BigInt.pm
@@ -2831,6 +2831,27 @@ sub __lcm
   }
 
 ###############################################################################
+# trigonometric functions
+
+sub bpi
+  {
+  # Calculate PI to N digits. Unless upgrading is in effect, returns the
+  # result truncated to an integer, that is, always returns '3'.
+  my ($self,$n) = @_;
+  if (@_ == 1)
+    {
+    # called like Math::BigInt::bpi(10);
+    $n = $self; $self = $class;
+    }
+  $self = ref($self) if ref($self);
+
+  return $upgrade->new($n) if defined $upgrade;
+
+  # hard-wired to "3"
+  $self->new(3);
+  }
+
+###############################################################################
 # this method returns 0 if the object can be modified, or 1 if not.
 # We use a fast constant sub() here, to avoid costly calls. Subclasses
 # may override it with special code (f.i. Math::BigInt::Constant does so)
@@ -2865,14 +2886,17 @@ Math::BigInt - Arbitrary size integer/float math package
   my $n = 1; my $sign = '-';
 
   # Number creation	
-  $x = Math::BigInt->new($str);		# defaults to 0
-  $y = $x->copy();			# make a true copy
-  $nan  = Math::BigInt->bnan(); 	# create a NotANumber
-  $zero = Math::BigInt->bzero();	# create a +0
-  $inf = Math::BigInt->binf();		# create a +inf
-  $inf = Math::BigInt->binf('-');	# create a -inf
-  $one = Math::BigInt->bone();		# create a +1
-  $one = Math::BigInt->bone('-');	# create a -1
+  my $x = Math::BigInt->new($str);	# defaults to 0
+  my $y = $x->copy();			# make a true copy
+  my $nan  = Math::BigInt->bnan(); 	# create a NotANumber
+  my $zero = Math::BigInt->bzero();	# create a +0
+  my $inf = Math::BigInt->binf();	# create a +inf
+  my $inf = Math::BigInt->binf('-');	# create a -inf
+  my $one = Math::BigInt->bone();	# create a +1
+  my $mone = Math::BigInt->bone('-');	# create a -1
+
+  my $pi = Math::BigInt->bpi();		# returns '3'
+					# see Math::BigFloat::bpi()
 
   $h = Math::BigInt->new('0x123');	# from hexadecimal
   $b = Math::BigInt->new('0b101');	# from binary
@@ -3497,6 +3521,23 @@ function. The result is equivalent to:
 
 This method was added in v1.84 of Math::BigInt (April 2007).
 
+=head2 bpi()
+
+	print Math::BigInt->bpi(100), "\n";		# 3
+
+Returns PI truncated to an integer, with the argument being ignored. that
+is it always returns C<3>.
+
+If upgrading is in effect, returns PI to N digits (including the "3"
+before the dot):
+
+	use Math::BigFloat;
+	use Math::BigInt upgrade => Math::BigFloat;
+	print Math::BigInt->bpi(3), "\n";		# 3.14
+	print Math::BigInt->bpi(100), "\n";		# 3.1415....
+
+This method was added in v1.87 of Math::BigInt (June 2007).
+
 =head2 blsft()
 
 	$x->blsft($y);		# left shift in base 2
@@ -4385,6 +4426,13 @@ All other methods upgrade themselves only when one (or all) of their
 arguments are of the class mentioned in $upgrade (This might change in later
 versions to a more sophisticated scheme):
 
+=head1 EXPORTS
+
+C<Math::BigInt> exports nothing by default, but can export the following methods:
+
+	bgcd
+	blcm
+
 =head1 BUGS
 
 =over 2