MirOS Manual: bigint(3p)

```
bigint(3p)      Perl Programmers Reference Guide       bigint(3p)
```

NAME

```     bigint - Transparent BigInteger support for Perl
```

SYNOPSIS

```       use bigint;

\$x = 2 + 4.5,"\n";                    # BigInt 6
print 2 ** 512,"\n";                  # really is what you think it is
print inf + 42,"\n";                  # inf
print NaN * 7,"\n";                   # NaN
```

DESCRIPTION

```     All operators (including basic math operations) are over-
loaded. Integer constants are created as proper BigInts.

Floating point constants are truncated to integer. All
results are also truncated.

Options

bigint recognizes some options that can be passed while
loading it via use. The options can (currently) be either a
single letter form, or the long form. The following options
exist:

a or accuracy
This sets the accuracy for all math operations. The argu-
ment must be greater than or equal to zero. See
Math::BigInt's bround() function for details.

perl -Mbigint=a,2 -le 'print 12345+1'

p or precision
This sets the precision for all math operations. The argu-
ment can be any integer. Negative values mean a fixed
number of digits after the dot, and are <B>ignored</B>
since all operations happen in integer space. A positive
value rounds to this digit left from the dot. 0 or 1 mean
round to integer and are ignore like negative values.

See Math::BigInt's bfround() function for details.

perl -Mbignum=p,5 -le 'print 123456789+123'

t or trace
This enables a trace mode and is primarily for debugging
bigint or Math::BigInt.

l or lib
Load a different math lib, see "MATH LIBRARY".

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

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Currently there is no way to specify more than one library
on the command line. This will be hopefully fixed soon ;)

v or version
This prints out the name and version of all modules used
and then exits.

perl -Mbigint=v

Math Library

Math with the numbers is done (by default) by a module
called Math::BigInt::Calc. This is equivalent to saying:

use bigint lib => 'Calc';

You can change this by using:

use bigint lib => 'BitVect';

The following would first try to find Math::BigInt::Foo,
then Math::BigInt::Bar, and when this also fails, revert to
Math::BigInt::Calc:

use bigint lib => 'Foo,Math::BigInt::Bar';

Please see respective module documentation for further
details.

Internal Format

The numbers are stored as objects, and their internals might
change at anytime, especially between math operations. The
objects also might belong to different classes, like
Math::BigInt, or Math::BigInt::Lite. Mixing them together,
even with normal scalars is not extraordinary, but normal
and expected.

You should not depend on the internal format, all accesses
must go through accessor methods. E.g. looking at \$x->{sign}
is not a good idea since there is no guaranty that the
object in question has such a hash key, nor is a hash under-
neath at all.

Sign

The sign is either '+', '-', 'NaN', '+inf' or '-inf'. You
can access it with the sign() method.

A sign of 'NaN' is used to represent the result when input
arguments are not numbers or as a result of 0/0. '+inf' and
'-inf' represent plus respectively minus infinity. You will

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get '+inf' when dividing a positive number by 0, and '-inf'
when dividing any negative number by 0.

Methods

Since all numbers are now objects, you can use all functions
that are part of the BigInt API. You can only use the bxxx()
notation, and not the fxxx() notation, though.

Caveat

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 beeing des-
troyed:

\$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 testthe 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 BigInt for further
details.
```

MODULES USED

```     "bigint" is just a thin wrapper around various modules of
the Math::BigInt family. Think of it as the head of the fam-
ily, who runs the shop, and orders the others to do the
work.

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The following modules are currently used by bigint:

Math::BigInt::Lite      (for speed, and only if it is loadable)
Math::BigInt
```

EXAMPLES

```     Some cool command line examples to impress the Python crowd
;) You might want to compare them to the results under
-Mbignum 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 3/7 + 5/7 + 8/3'
perl -Mbigint -le 'print 123->is_odd()'
perl -Mbigint -le 'print log(2)'
perl -Mbigint -le 'print 2 ** 0.5'
perl -Mbigint=a,65 -le 'print 2 ** 0.2'
```

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

```     Especially bigrat as in "perl -Mbigrat -le 'print 1/3+1/4'"
and bignum as in "perl -Mbignum -le 'print sqrt(2)'".

Math::BigInt, Math::BigRat and Math::Big as well as
Math::BigInt::BitVect, Math::BigInt::Pari and
Math::BigInt::GMP.
```

AUTHORS

```     (C) by Tels <http://bloodgate.com/> in early 2002 - 2005.

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```

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