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bigint(3pm)            Perl Programmers Reference Guide            bigint(3pm)



NAME

       bigint - transparent big integer support for Perl


SYNOPSIS

           use bigint;

           $x = 2 + 4.5;                       # Math::BigInt 6
           print 2 ** 512;                     # Math::BigInt 134...096
           print inf + 42;                     # Math::BigInt inf
           print NaN * 7;                      # Math::BigInt NaN
           print hex("0x1234567890123490");    # Perl v5.10.0 or later

           {
               no bigint;
               print 2 ** 256;                 # a normal Perl scalar now
           }

           # for older Perls, import into current package:
           use bigint qw/hex oct/;
           print hex("0x1234567890123490");
           print oct("01234567890123490");


DESCRIPTION

       All numeric literal in the given scope are converted to Math::BigInt
       objects.  Numeric literal that represent non-integers are truncated to
       an integer. All results of expressions are also truncated to integer.

       All operators (including basic math operations) except the range
       operator ".." are overloaded.

       Unlike the integer pragma, the "bigint" pragma creates integers that
       are only limited in their size by the available memory.

       So, the following:

           use bigint;
           $x = 1234;

       creates a Math::BigInt 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 -Mbigint -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 -Mbigint -le '$x = 1234; print $x->bdec()'
           perl -Mbigint -le 'print 1234->copy()->binc();'
           perl -Mbigint -le 'print 1234->copy()->binc->badd(6);'
           perl -Mbigint -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 -Mbigint -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 -Mbigint -le 'for (1..2) { print ref($_); }'

   use integer vs. use bigint
       There are some difference between "use integer" and "use bigint".

       Whereas "use integer" is limited to what can be handled as a Perl
       scalar, "use bigint" can handle arbitrarily large integers.

       Also, "use integer" does affect assignments to variables and the return
       value of some functions. "use bigint" truncates these results to
       integer:

           # perl -Minteger -wle 'print 3.2'
           3.2
           # perl -Minteger -wle 'print 3.2 + 0'
           3
           # perl -Mbigint -wle 'print 3.2'
           3
           # perl -Mbigint -wle 'print 3.2 + 0'
           3

           # perl -Mbigint -wle 'print exp(1) + 0'
           2
           # perl -Mbigint -wle 'print exp(1)'
           2
           # perl -Minteger -wle 'print exp(1)'
           2.71828182845905
           # perl -Minteger -wle 'print exp(1) + 0'
           2

       In practice this seldom makes a difference for small integers as parts
       and results of expressions are truncated anyway, but this can, for
       instance, affect the return value of subroutines:

           sub three_integer { use integer; return 3.2; }
           sub three_bigint { use bigint; return 3.2; }

           print three_integer(), " ", three_bigint(),"\n";    # prints "3.2 3"

   Options
       "bigint" recognizes some options that can be passed while loading it
       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 -Mbigint=a,2 -le 'print 12345+1'

           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, and are ignored since all operations happen in integer
           space. 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 -mbigint=p,5 -le 'print 123456789+123'

           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 -Mbigint=l,GMP -e 'print 2 ** 512'
               perl -Mbigint=lib,GMP -e 'print 2 ** 512'
               perl -Mbigint=try,GMP -e 'print 2 ** 512'
               perl -Mbigint=only,GMP -e 'print 2 ** 512'

       hex Override the built-in 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 necessary, as
           hex() is lexically overridden in the current scope whenever the
           "bigint" pragma is active.

       oct Override the built-in 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
           "bigint" pragma is active.

       v or version
           this prints out the name and version of the modules and then exits.

               perl -Mbigint=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 bigint lib => 'Calc';

       you can change this by using:

           use bigint 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 bigint 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 bigint try => 'GMP';

       If you want the code to die instead of falling back, use "only"
       instead:

           use bigint only => 'GMP';

       Please see the 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::BigInt 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::BigInt for further details.

   Methods
       inf()
           A shortcut to return Math::BigInt->binf(). Useful because Perl does
           not always handle bareword "inf" properly.

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

       e
               # perl -Mbigint=e -wle 'print e'

           Returns Euler's number "e", aka exp(1). Note that under "bigint",
           this is truncated to an integer, i.e., 2.

       PI
               # perl -Mbigint=PI -wle 'print PI'

           Returns PI. Note that under "bigint", this is truncated to an
           integer, i.e., 3.

       bexp()
               bexp($power, $accuracy);

           Returns Euler's number "e" raised to the appropriate power, to the
           wanted accuracy.

           Note that under "bigint", the result is truncated to an integer.

           Example:

               # perl -Mbigint=bexp -wle 'print bexp(1,80)'

       bpi()
               bpi($accuracy);

           Returns PI to the wanted accuracy. Note that under "bigint", this
           is truncated to an integer, i.e., 3.

           Example:

               # perl -Mbigint=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.

       in_effect()
               use bigint;

               print "in effect\n" if bigint::in_effect;       # true
               {
                   no bigint;
                   print "in effect\n" if bigint::in_effect;   # false
               }

           Returns true or false if "bigint" 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
           "bigint" works by overloading handling of integer and floating
           point literals, converting them to Math::BigInt objects.

           This means that arithmetic involving only string values or string
           literals are performed using Perl's built-in operators.

           For example:

               use bigint;
               my $x = "900000000000000009";
               my $y = "900000000000000007";
               print $x - $y;

           outputs 0 on default 32-bit builds, since "bigint" never sees the
           string literals. To ensure the expression is all treated as
           "Math::BigInt" 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 "bigint" endpoints, nor is the iterator
           variable a "Math::BigInt".

               use 5.010;
               for my $i (12..13) {
                 for my $j (20..21) {
                   say $i ** $j;  # produces a floating-point number,
                                  # not an object
                 }
               }

       in_effect()
           This method only works on Perl v5.9.4 or later.

       hex()/oct()
           "bigint" 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 with "no bigint":

               use bigint qw/hex oct/;

               print hex("0x1234567890123456");
               {
                   no bigint;
                   print hex("0x1234567890123456");
               }

           The second call to hex() will warn about a non-portable constant.

           Compare this to:

               use bigint;

               # will warn only under Perl older than v5.9.4
               print hex("0x1234567890123456");


EXAMPLES

       Some cool command line examples to impress the Python crowd ;) You
       might want to compare them to the results under -Mbigfloat or -Mbigrat:

           perl -Mbigint -le 'print sqrt(33)'
           perl -Mbigint -le 'print 2**255'
           perl -Mbigint -le 'print 4.5+2**255'
           perl -Mbigint -le 'print 123->is_odd()'
           perl -Mbigint=l,GMP -le 'print 7 ** 7777'


BUGS

       Please report any bugs or feature requests to "bug-bignum 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 bigint

       You can also look for information at:

       o   GitHub

           <https://github.com/pjacklam/p5-bignum>

       o   RT: CPAN's request tracker

           <https://rt.cpan.org/Dist/Display.html?Name=bignum>

       o   MetaCPAN

           <https://metacpan.org/release/bignum>

       o   CPAN Testers Matrix

           <http://matrix.cpantesters.org/?dist=bignum>

       o   CPAN Ratings

           <https://cpanratings.perl.org/dist/bignum>


LICENSE

       This program is free software; you may redistribute it and/or modify it
       under the same terms as Perl itself.


SEE ALSO

       bignum(3) and bigrat(3).

       Math::BigInt(3), Math::BigFloat(3), Math::BigRat(3) and Math::Big(3) as
       well as Math::BigInt::FastCalc(3), Math::BigInt::Pari(3) and
       Math::BigInt::GMP(3).


AUTHORS

       o   (C) by Tels <http://bloodgate.com/> in early 2002 - 2007.

       o   Maintained by Peter John Acklam <pjacklam@gmail.com>, 2014-.

perl v5.38.2                      2023-11-28                       bigint(3pm)

perl 5.38.2 - Generated Sun Dec 15 13:15:25 CST 2024
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