#!/usr/bin/perl
use strict;
use warnings;

$a = "12.2424.4812367";

$a =~ s/(?x)
	(
		(?# match integer and floating point numbers )
		(?: \d+ (?: \. \d+ )? )
	)
	(
		(?# execute code, match result )
		(??{
			## return twice the first argument
			sub{ shift() * 2 }->( $1 ) 
		})
	)
	/
		## print the arguments as a couple
		sub{ join( '', '(', shift(), ',', shift(), ')' ) }->( $1, $2 )
	/ge;

print $a;

##</code><code>##

.