Math::Fleximal - Integers with flexible representations.
use Math::Fleximal;
my $number = new Math::Fleximal($value, $flex);
# Set the value
$number = $number->set_value("- $fleck_4$fleck_3");
$number = $number->set_value($another_number);
# Get the object in a familiar form
my $string = $number->to_str();
my $integer = $number->base_10();
# Construct more numbers with same flex
my $copy = $number->dup();
my $other_number = $number->dup($value);
my $absolute_value = $number->abs();
# New representation anyone?
my $in_new_base = $number->change_flex($new_flex);
# Arithmetic - can be different flex. Answers have
# the flex of $number.
$result = $number->add($other_number);
$result = $number->mul($other_number);
$result = $number->subtr($other_numer);
$result = $number->div($other_number);
# And integer-specific arithmetic works
$result = $number->gcd($other_number);
$result = $number->mod($other_number);
my $comparison = $number->cmp($other_number);
This is a package for doing integer arithmetic while using a different base
representation than normal. In base n arithmetic you have n symbols which have
a representation. I was going to call them "glyphs", but being text
strings they are not really. On Tye McQueen's whimsical suggestion I settled
on the name Math::Fleximal, the set of text representations is called a
"flex", and the representation of individual digits are the
"flecks". These names are somewhat unofficial...
This allows you to do basic arithmetic using whatever digits you
want, and to convert from one to another.
Like "Math::BigInt" it is able
to handle very large numbers, though performance is not very good. (Which is
also like "Math::BigInt", for good
performance you should be using <Bit::Vector>.) Instead use it as a
version of Math::BaseCalc without an upper limit on the size of numbers. A
sample use would be to put an MD5 hash into a convenient representation:
use Math::Fleximal;
use Digest::MD5 qw(md5_hex);
my $digest = hex2alpha(md5_hex($data));
# Converts a hex representation of a number into
# one that uses more alphanumerics. (ie base 62)
sub hex2alpha {
Math::Fleximal->new(
lc(shift), [0..9, 'a'..'f']
)->change_flex(
[0..9,'a'..'z','A'..'Z']
)->to_str();
}
- "new"
- Construct a new number. The arguments are the value, the anonymous array
of flecks that make up the flex, followed by an anonymous hash of other
arguments. The flex will default to [0..9] and the other arguments will
default to an empty hash.
This can be used to calculations in bases other than 10 - the
base is just the number of flecks in the flex. So you could construct a
base 16 number with:
my $base_16 = new Math::Fleximal("4d", [0..9, 'a'..'f']);
If a value is passed it can be an existing Math::Fleximal or
(as above) a string that can be parsed with the current flex.
The possible keys to the optional arguments are:
- + for the plus symbol to use. This defaults to '+'.
- - for the minus symbol to use. This defaults to '-'.
- show_+ is a flag for whether to show the plus symbol on positive
numbers. This defaults to a false value.
- Whatever matches strip will be stripped from the string before
parsing. This defaults to qr/[\s\.,_]/ to cover most of the common ways
that are used to group digits in a long number.
The parsing of a string into flecks is case sensitive. Also
possibly ambiguous parses are not handled very well.
- "dup"
- Copy an existing number. This copy may be worked with without changing the
existing number. If dup is passed a value, the new instance will have that
value instead.
- "set_value"
- This sets the internal value and returns the object.
You can either pass the new value an existing instance (which
may be in another base) or a string. When passed a string it first
strips whitespace. After that it accepts an optional +-, followed by a
series of flecks (there must be at least one) for the first to last
digits. It will be confused if the leading fleck starts with + or - and
no sign is included.
- "to_str"
- Returns the string representation of the current value using the current
flex. This always includes a sign, with no white space in front of the
sign.
- "base_10"
- Returns the internal value in a base 10 representation. The numbers
returned may be larger than Perl's usual integer representation can
handle.
- "change_flex"
- Takes a new flex and converts the current to that. Will implicitly change
base if needed.
- "add"
- Adds one or more numbers to the current one and returns the answer in the
current representation. The numbers may be objects in any base, or strings
of the current representation.
- "mul"
- Multiplies one or more numbers to the current one and returns the answer
in the current representation. The numbers may be objects in any base, or
strings of the current representation.
- "subtr"
- Subtracts one or more numbers from the current one and returns the answer
in the current representation. The numbers may be objects in any base, or
strings of the current representation.
- "div"
- Divides one or more numbers from the current one and returns the answer in
the current representation. In list context it will return the answer and
an array of remainders in the current representation. The remainders will
be positive and less than the absolute value of the denominator. The
numbers may be objects in any base, or strings of the current
representation.
- "gcd"
- Takes one or more numbers and calculates the gcd of this and the entire
list.
- "mod"
- Does the divisions as "div" does and
returns only the remainders. In scalar context only the last remainder is
returned. Thus the following returns the ten-thousands digit:
my $digit = $number->mod(1000, 10);
- "cmp"
- Pass another number, returns -1 if it is smaller than the other number, 0
if they are equal, and 1 if it is larger. (Much like cmp does with
strings.)
- "one"
- Returns 1 in the current flex.
- "zero"
- Returns 0 in the current flex.
This will fail if you are trying to work in bases of size more than 30,000 or
so.
Only a slight effort is made to resolve potential ambiguities in
the parsing of a string into flecks.
Copyright 2000-2001, Ben Tilly (<btilly@gmail.com>)
Math::Fleximal may be copied and distributed on the same terms as
Perl itself.