#!/usr/bin/octave -qf
% Copyright 2005 Daniel Cer (daniel.cer@cs.colorado.edu)
%
% This work is licensed under the Creative Commons Attribution-NonCommercial-
% ShareAlike License. To view a copy of this license, visit 
% http://creativecommons.org/licenses/by-nc-sa/2.5/ or send a letter to 
% Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 
% 94105, USA.

function fib=fibonacci(n)
  if n <= 0, fib=-1; return; endif
  prev_fib = 1; fib = 1;
  for i=3:n,
    next_prev_fib = fib; fib += prev_fib; prev_fib = next_prev_fib;
  endfor 
endfunction

if nargin != 1, 
   fprintf(stderr, 
      "Usage:\n\t%s (n-th fibonacci # to calculate)\n", program_name);
   exit
endif 

n = str2num(argv{1});

printf("fibonacci(%d): %d\n", n, fibonacci(n));