NAME
bigfloat  transparent big floating point number support for Perl
SYNOPSIS
use bigfloat;
$x = 2 + 4.5; # Math::BigFloat 6.5
print 2 ** 512 * 0.1; # Math::BigFloat 134...09.6
print inf + 42; # Math::BigFloat inf
print NaN * 7; # Math::BigFloat NaN
print hex("0x1234567890123490"); # Perl v5.10.0 or later
{
no bigfloat;
print 2 ** 256; # a normal Perl scalar now
}
# for older Perls, import into current package:
use bigfloat qw/hex oct/;
print hex("0x1234567890123490");
print oct("01234567890123490");
DESCRIPTION
All numeric literals in the given scope are converted to Math::BigFloat objects.
All operators (including basic math operations) except the range operator ..
are overloaded.
So, the following:
use bigfloat;
$x = 1234;
creates a Math::BigFloat and stores a reference to in $x. This happens transparently and behind your back, so to speak.
You can see this with the following:
perl Mbigfloat le 'print ref(1234)'
Since numbers are actually objects, you can call all the usual methods from Math::BigFloat on them. This even works to some extent on expressions:
perl Mbigfloat le '$x = 1234; print $x>bdec()'
perl Mbigfloat le 'print 1234>copy()>binc();'
perl Mbigfloat le 'print 1234>copy()>binc>badd(6);'
perl Mbigfloat le 'print +(1234)>copy()>binc()'
(Note that print doesn't do what you expect if the expression starts with '(' hence the +
)
You can even chain the operations together as usual:
perl Mbigfloat le 'print 1234>copy()>binc>badd(6);'
1241
Please note the following does not work as expected (prints nothing), since overloading of '..' is not yet possible in Perl (as of v5.8.0):
perl Mbigfloat le 'for (1..2) { print ref($_); }'
Options
bigfloat
recognizes some options that can be passed while loading it via via use
. The following options exist:
 a or accuracy

This sets the accuracy for all math operations. The argument must be greater than or equal to zero. See Math::BigInt's bround() method for details.
perl Mbigfloat=a,50 le 'print sqrt(20)'
Note that setting precision and accuracy at the same time is not possible.
 p or precision

This sets the precision for all math operations. The argument can be any integer. Negative values mean a fixed number of digits after the dot, while a positive value rounds to this digit left from the dot. 0 means round to integer. See Math::BigInt's bfround() method for details.
perl Mbigfloat=p,50 le 'print sqrt(20)'
Note that setting precision and accuracy at the same time is not possible.
 t or trace

This enables a trace mode and is primarily for debugging.
 l, lib, try, or only

Load a different math lib, see "Math Library".
perl Mbigfloat=l,GMP e 'print 2 ** 512' perl Mbigfloat=lib,GMP e 'print 2 ** 512' perl Mbigfloat=try,GMP e 'print 2 ** 512' perl Mbigfloat=only,GMP e 'print 2 ** 512'
 hex

Override the builtin hex() method with a version that can handle big numbers. This overrides it by exporting it to the current package. Under Perl v5.10.0 and higher, this is not so necessary, as hex() is lexically overridden in the current scope whenever the
bigfloat
pragma is active.  oct

Override the builtin oct() method with a version that can handle big numbers. This overrides it by exporting it to the current package. Under Perl v5.10.0 and higher, this is not so necessary, as oct() is lexically overridden in the current scope whenever the
bigfloat
pragma is active.  v or version

this prints out the name and version of the modules and then exits.
perl Mbigfloat=v
Math Library
Math with the numbers is done (by default) by a backend library module called Math::BigInt::Calc. The default is equivalent to saying:
use bigfloat lib => 'Calc';
you can change this by using:
use bigfloat lib => 'GMP';
The following would first try to find Math::BigInt::Foo, then Math::BigInt::Bar, and if this also fails, revert to Math::BigInt::Calc:
use bigfloat lib => 'Foo,Math::BigInt::Bar';
Using c<lib> warns if none of the specified libraries can be found and Math::BigInt fell back to one of the default libraries. To suppress this warning, use c<try> instead:
use bigfloat try => 'GMP';
If you want the code to die instead of falling back, use only
instead:
use bigfloat only => 'GMP';
Please see respective module documentation for further details.
Method calls
Since all numbers are now objects, you can use all methods that are part of the Math::BigFloat API.
But a warning is in order. When using the following to make a copy of a number, only a shallow copy will be made.
$x = 9; $y = $x;
$x = $y = 7;
Using the copy or the original with overloaded math is okay, e.g., the following work:
$x = 9; $y = $x;
print $x + 1, " ", $y,"\n"; # prints 10 9
but calling any method that modifies the number directly will result in both the original and the copy being destroyed:
$x = 9; $y = $x;
print $x>badd(1), " ", $y,"\n"; # prints 10 10
$x = 9; $y = $x;
print $x>binc(1), " ", $y,"\n"; # prints 10 10
$x = 9; $y = $x;
print $x>bmul(2), " ", $y,"\n"; # prints 18 18
Using methods that do not modify, but test that the contents works:
$x = 9; $y = $x;
$z = 9 if $x>is_zero(); # works fine
See the documentation about the copy constructor and =
in overload, as well as the documentation in Math::BigFloat for further details.
Methods
 inf()

A shortcut to return Math::BigFloat>binf(). Useful because Perl does not always handle bareword
inf
properly.  NaN()

A shortcut to return Math::BigFloat>bnan(). Useful because Perl does not always handle bareword
NaN
properly.  e

# perl Mbigfloat=e wle 'print e'
Returns Euler's number
e
, aka exp(1)  PI

# perl Mbigfloat=PI wle 'print PI'
Returns PI.
 bexp()

bexp($power, $accuracy);
Returns Euler's number
e
raised to the appropriate power, to the wanted accuracy.Example:
# perl Mbigfloat=bexp wle 'print bexp(1,80)'
 bpi()

bpi($accuracy);
Returns PI to the wanted accuracy.
Example:
# perl Mbigfloat=bpi wle 'print bpi(80)'
 accuracy()

Set or get the accuracy.
 precision()

Set or get the precision.
 round_mode()

Set or get the rounding mode.
 div_scale()

Set or get the division scale.
 upgrade()

Set or get the class that the downgrade class upgrades to, if any. Set the upgrade class to
undef
to disable upgrading.Upgrading is disabled by default.
 downgrade()

Set or get the class that the upgrade class downgrades to, if any. Set the downgrade class to
undef
to disable upgrading.Downgrading is disabled by default.
 in_effect()

use bigfloat; print "in effect\n" if bigfloat::in_effect; # true { no bigfloat; print "in effect\n" if bigfloat::in_effect; # false }
Returns true or false if
bigfloat
is in effect in the current scope.This method only works on Perl v5.9.4 or later.
CAVEATS
 Hexadecimal, octal, and binary floating point literals

Perl (and this module) accepts hexadecimal, octal, and binary floating point literals, but use them with care with Perl versions before v5.32.0, because some versions of Perl silently give the wrong result.
 Operator vs literal overloading

bigrat
works by overloading handling of integer and floating point literals, converting them to Math::BigRat objects.This means that arithmetic involving only string values or string literals are performed using Perl's builtin operators.
For example:
use bigrat; my $x = "900000000000000009"; my $y = "900000000000000007"; print $x  $y;
outputs
0
on default 32bit builds, sincebigfloat
never sees the string literals. To ensure the expression is all treated asMath::BigFloat
objects, use a literal number in the expression:print +(0+$x)  $y;
 Ranges

Perl does not allow overloading of ranges, so you can neither safely use ranges with
bigfloat
endpoints, nor is the iterator variable aMath::BigFloat
.use 5.010; for my $i (12..13) { for my $j (20..21) { say $i ** $j; # produces a floatingpoint number, # not an object } }
 in_effect()

This method only works on Perl v5.9.4 or later.
 hex()/oct()

bigfloat
overrides these routines with versions that can also handle big integer values. Under Perl prior to version v5.9.4, however, this will not happen unless you specifically ask for it with the two import tags "hex" and "oct"  and then it will be global and cannot be disabled inside a scope withno bigfloat
:use bigfloat qw/hex oct/; print hex("0x1234567890123456"); { no bigfloat; print hex("0x1234567890123456"); }
The second call to hex() will warn about a nonportable constant.
Compare this to:
use bigfloat; # will warn only under Perl older than v5.9.4 print hex("0x1234567890123456");
EXAMPLES
Some cool command line examples to impress the Python crowd ;)
perl Mbigfloat le 'print sqrt(33)'
perl Mbigfloat le 'print 2**255'
perl Mbigfloat le 'print 4.5+2**255'
perl Mbigfloat le 'print 3/7 + 5/7 + 8/3'
perl Mbigfloat le 'print 123>is_odd()'
perl Mbigfloat le 'print log(2)'
perl Mbigfloat le 'print exp(1)'
perl Mbigfloat le 'print 2 ** 0.5'
perl Mbigfloat=a,65 le 'print 2 ** 0.2'
perl Mbigfloat=l,GMP le 'print 7 ** 7777'
BUGS
Please report any bugs or feature requests to bugbignum at rt.cpan.org
, or through the web interface at https://rt.cpan.org/Ticket/Create.html?Queue=bignum (requires login). We will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc bigfloat
You can also look for information at:
GitHub
RT: CPAN's request tracker
MetaCPAN
CPAN Testers Matrix
LICENSE
This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
SEE ALSO
Math::BigInt, Math::BigFloat, Math::BigRat and Math::Big as well as Math::BigInt::FastCalc, Math::BigInt::Pari and Math::BigInt::GMP.
AUTHORS
(C) by Tels http://bloodgate.com/ in early 2002  2007.
Maintained by Peter John Acklam <pjacklam@gmail.com>, 2014.