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

my @array = (3.987654321,-3.987654321);

foreach $_ (@array){
    if ($_ < 0) {
	print "Value: $_ is negative\n";
	my $negative_b = dec2bin($_,64,"F");
	print "Negative binary: ".$negative_b."\n";
	my $negative_d = bin2dec($negative_b,64,"F");
	print "Negative_binary back to decimal: ".$negative_d."\n";
    }
    else {
	print "Value: $_ is possitive\n";
	my $possitive_b = dec2bin($_,64,"F");
	print "Possitive binary: ".$possitive_b."\n";
	my $possitive_d = bin2dec($possitive_b,64,"F");
	print "Possitive_binary back to decimal: ".$possitive_d."\n";
    }
}

sub dec2bin {
    my $bits     = shift;
    my $size     = shift;
    my $template = shift;
    my $str = unpack("B$size", pack($template, $bits));
    print "Substring: ".$str."\n";
    return $str;
}

sub bin2dec {
    my $bits     = shift;
    my $size     = shift;
    my $template = shift;
    return unpack($template, pack("B$size", substr("0" x $size . $bits , -$size)));
}

__END__

Value: 3.987654321 is possitive
Substring: 1010111010010101000000110100111110110111111001100000111101000000
Possitive binary: 1010111010010101000000110100111110110111111001100000111101000000
Possitive_binary back to decimal: 3.987654321
Value: -3.987654321 is negative
Substring: 1010111010010101000000110100111110110111111001100000111111000000
Negative binary: 1010111010010101000000110100111110110111111001100000111111000000
Negative_binary back to decimal: -3.987654321