NAME¶

Number::Fraction - Perl extension to model fractions

SYNOPSIS¶

  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'

ABSTRACT¶

Number::Fraction is a Perl module which allows you to work with fractions in your Perl programs.

DESCRIPTION¶

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'.

Experimental Support for Exponentiation¶

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)

METHODS¶

import¶

Called when module is "use"d. Use to optionally install constant handler.

unimport¶

Be a good citizen and uninstall constant handler when caller uses "no Number::Fraction".

new¶

Constructor for Number::Fraction object. Takes the following kinds of parameters:

•

A single Number::Fraction object which is cloned.

•

A string in the form 'x/y' where x and y are integers. x is used as the numerator and y is used as the denominator of the new object.

•

Two integers which are used as the numerator and denominator of the new object.

•

A single integer which is used as the numerator of the the new object. The denominator is set to 1.

•

No arguments, in which case a numerator of 0 and a denominator of 1 are used.

Returns "undef" if a Number::Fraction object can't be created.

to_string¶

Returns a string representation of the fraction in the form "numerator/denominator".

to_num¶

Returns a numeric representation of the fraction by calculating the sum numerator/denominator. Normal caveats about the precision of floating point numbers apply.

add¶

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.

mult¶

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¶

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.

div¶

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.

exp¶

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.

abs¶

Returns a copy of the given object with both the numerator and denominator changed to positive values.

EXPORT¶

None by default.

SEE ALSO¶

perldoc overload

AUTHOR¶

Dave Cross, <dave@mag-sol.com>

COPYRIGHT AND LICENSE¶

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.