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
print hex("0x1234567890123490"),"\n"; # Perl v5.10.0 or later
{
no bigint;
print 2 ** 256,"\n"; # a normal Perl scalar now
}
# Import into current package:
use bigint qw/hex oct/;
print hex("0x1234567890123490"),"\n";
print oct("01234567890123490"),"\n";
Floating point constants are truncated to integer. All parts and results of expressions are also truncated.
Unlike integer, this pragma creates integer constants that are only limited in their size by the available memory and CPU time.
# 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 makes seldom a difference as parts and results of expressions will be 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"
perl -Mbigint=a,2 -le 'print 12345+1'
Note that setting precision and accuracy at the same time is not possible.
See Math::BigInt's bfround() function for details.
perl -Mbignum=p,5 -le 'print 123456789+123'
Note that setting precision and accuracy at the same time is not possible.
perl -Mbigint=lib,GMP -e 'print 2 ** 512'
perl -Mbigint=try,GMP -e 'print 2 ** 512'
perl -Mbigint=only,GMP -e 'print 2 ** 512'
Currently there is no way to specify more than one library on the command line. This means the following does not work:
perl -Mbignum=l,GMP,Pari -e 'print 2 ** 512'
This will be hopefully fixed soon ;)
perl -Mbigint=v
use bigint lib => 'Calc';
You can change this by using:
use bignum lib => 'GMP';
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';
Using "lib" warns if none of the specified libraries can be found and Math::BigInt did fall back to one of the default libraries. To suppress this warning, use "try" instead:
use bignum try => 'GMP';
If you want the code to die instead of falling back, use "only" instead:
use bignum only => 'GMP';
Please see respective module documentation for further details.
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 underneath at all.
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 get '+inf' when dividing a positive number by 0, and '-inf' when dividing any negative number by 0.
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 $x->is_zero(); # works fine
See the documentation about the copy constructor and "=" in overload, as well as the documentation in BigInt for further details.
# perl -Mbigint=e -wle 'print e'
Returns Euler's number "e", aka exp(1). Note that under bigint, this is truncated to an integer, and hence simple '2'.
# perl -Mbigint=PI -wle 'print PI'
Returns PI. Note that under bigint, this is truncated to an integer, and hence simple '3'.
bexp($power,$accuracy);
Returns Euler's number "e" raised to the appropriate power, to the wanted accuracy.
Note that under bigint, the result is truncated to an integer.
Example:
# perl -Mbigint=bexp -wle 'print bexp(1,80)'
bpi($accuracy);
Returns PI to the wanted accuracy. Note that under bigint, this is truncated to an integer, and hence simple '3'.
Example:
# perl -Mbigint=bpi -wle 'print bpi(80)'
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.
This means that arithmetic involving only string values or string literals will be performed using Perl's built-in operators.
For example:
use bignum;
my $x = "900000000000000009";
my $y = "900000000000000007";
print $x - $y;
will output 0 on default 32-bit builds, since "bigint" never sees the string literals. To ensure the expression is all treated as "Math::BigInt" objects, use a literal number in the expression:
print +(0+$x) - $y;
use 5.010;
for my $i (12..13) {
for my $j (20..21) {
say $i ** $j; # produces a floating-point number,
# not a big integer
}
}
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");
The following modules are currently used by bigint:
Math::BigInt::Lite (for speed, and only if it is loadable)
Math::BigInt
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'
perl -Mbignum=a,65,l,GMP -le 'print 7 ** 7777'
perldoc bignum
perldoc bigint
For more information, see the SUPPORT section in the documentation available with the perldoc command.
perldoc bignum
Math::BigInt, Math::BigFloat, Math::BigRat and Math::Big as well as Math::BigInt::FastCalc, Math::BigInt::Pari and Math::BigInt::GMP.