I thought this code looked a bit odd, so I took the trouble to install Math::Big and play with it.

1. I think you have an "off by one" problem. $fibonacci[$n-1] does not appear to be correct.
2. The need for the fib subroutine is unclear to me.
3. This fibonacci subroutine in the Math::Big library appears to be so fast, that the need for Memoize is also unclear to me...this thing barfs out fibonacci(1000) with incredible speed!

Below is my testing code: 

#!/usr/bin/perl

use strict;
use warnings;
use Math::Big qw/fibonacci/;

my $n=6;

print scalar(fibonacci($n)), "\n";
print "".fibonacci($n), "\n";  #another way to force scalar context
my @fibs = fibonacci($n);
print "@fibs\n";
print $fibs[-1],"\n";  #NOT $n-1, [$n] same as [-1] here.

foreach (1000,2000,3000)
{
   #print "".fibonacci($_), "\n\n";
   #prints HUGE numbers not shown below
}

__END__
prints:
.....testing the fibonacci of 6, which is indeed 8....
8
8
0 1 1 2 3 5 8
8

[download]
Anyway, I figure that we are getting pretty "far into the outfield" on this one. Yes, there is a library function for generating a fibonacci number. Yes, it is very fast. Yes, it can calculate these numbers to an incredible number of digits. No, it does not use a recursive algorithm. The library function likes to start the sequence at 0 instead of 1, but that is allowed within the definition of the sequence. Of course it is completely possible that I've misunderstood something - wouldn't be the first time...let me know.

In reply to Re^4: fibonacci numbers using subroutine? by Marshall
in thread fibonacci numbers using subroutine? by derpp

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