This is an unnecessary obfuscation for no apparent reason. The statement albeit short is very obtuse.
JavaFan has given a great explanation of how this obscure thing works.
A Perl implementation of a more traditional and MUCH faster approach is below. Perl allows very obscure looking code to be written, but why do it?
#!/usr/bin/perl -w
use strict;
foreach (1..15)
{
print fibonacci($_), " ";
}
# prints: 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610
sub fibonacci
{
my $number = shift;
my $cur_num = 1;
my $prev_num = 1;
my $sum;
return 1 if ($number == 1 || $number == 2);
# to get Op's output, supress the above by this:
# return "" if ($number == 1 || $number == 2);
# or of course just start the sequence at a different number
$number -= 2;
while ($number--)
{
$sum = $cur_num + $prev_num;
$prev_num = $cur_num;
$cur_num = $sum;
}
return $sum;
}
