Number::Fraction - Perl extension to model fractions
use Number::Fraction;
my $f1 = Number::Fraction->new(1, 2);
my $f2 = Number::Fraction->new('1/2');
my $f3 = Number::Fraction->new($f1); # clone
my $f4 = Number::Fraction->new; # 0/1
or
use Number::Fraction ':constants'; my $f1 = '1/2'; my $f2 = $f1; my $one = $f1 + $f2; my $half = $one - $f1; print $half; # prints '1/2'
Number::Fraction is a Perl module which allows you to work with fractions in your Perl programs.
Number::Fraction allows you to work with fractions (i.e. rational numbers) in your Perl programs in a very natural way.
It was originally written as a demonstration of the techniques of overloading.
If you use the module in your program in the usual way
use Number::Fraction;
you can then create fraction objects using Number::Fraction-new> in a number of ways.
my $f1 = Number::Fraction->new(1, 2);
creates a fraction with a numerator of 1 and a denominator of 2.
my $f2 = Number::Fraction->new('1/2');
does the same thing but from a string constant.
my $f3 = Number::Fraction->new($f1);
makes $f3 a copy of $f1
my $f4 = Number::Fraction->new; # 0/1
creates a fraction with a denominator of 0 and a numerator of 1.
If you use the alterative syntax of
use Number::Fraction ':constants';
then Number::Fraction will automatically create fraction objects from string constants in your program. Any time your program contains a string constant of the form \d+/\d+ then that will be automatically replaced with the equivalent fraction object. For example
my $f1 = '1/2';
Having created fraction objects you can manipulate them using most of the normal mathematical operations.
my $one = $f1 + $f2; my $half = $one - $f1;
Additionally, whenever a fraction object is evaluated in a string context, it will return a string in the format x/y. When a fraction object is evaluated in a numerical context, it will return a floating point representation of its value.
Fraction objects will always "normalise" themselves. That is, if you create a fraction of '2/4', it will silently be converted to '1/2'.
Version 1.13 of Number::Fraction adds experimental support for exponentiation operations. If a Number::Fraction object is used as the left hand operand of an exponentiation expression then the value returned will be another Number::Fraction object - if that makes sense. In all other cases, the expression returns a real number.
Currently this only works if the right hand operand is an integer (or a Number::Fraction object that has a denominator of 1). Later I hope to extend this so support so that a Number::Fraction object is returned whenever the result of the expression is a rational number.
For example:
'1/2' ** 2 # Returns a Number::Fraction ('1/4')
'2/1' ** '2/1' Returns a Number::Fraction ('4/1')
'2/1' ** '1/2' Returns a real number (1.414213)
0.5 ** '2/1' Returns a real number (0.25)
Called when module is used. Use to optionally install constant handler.
Be a good citizen and uninstall constant handler when caller uses no Number::Fraction.
Constructor for Number::Fraction object. Takes the following kinds of parameters:
Returns undef if a Number::Fraction object can't be created.
Returns a string representation of the fraction in the form "numerator/denominator".
Returns a numeric representation of the fraction by calculating the sum numerator/denominator. Normal caveats about the precision of floating point numbers apply.
Add a value to a fraction object and return a new object representing the result of the calculation.
The first parameter is a fraction object. The second parameter is either another fraction object or a number.
Multiply a fraction object by a value and return a new object representing the result of the calculation.
The first parameter is a fraction object. The second parameter is either another fraction object or a number.
Subtract a value from a fraction object and return a new object representing the result of the calculation.
The first parameter is a fraction object. The second parameter is either another fraction object or a number.
Divide a fraction object by a value and return a new object representing the result of the calculation.
The first parameter is a fraction object. The second parameter is either another fraction object or a number.
Raise a Number::Fraction object to a power.
The first argument is a number fraction object. The second argument is another Number::Fraction object or a number. If the second argument is an integer or a Number::Fraction object containing an integer then the value returned is a Number::Fraction object, otherwise the value returned is a real number.
Returns a copy of the given object with both the numerator and denominator changed to positive values.
None by default.
perldoc overload
Dave Cross, <dave@mag-sol.com>
Copyright 2002-8 by Dave Cross
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
