Function Math.fibonacci

Find the nth Fibonacci number.

• Syntax Number Math.fibonacci(Number n )
  
  This function will return the nth Fibonacci number. Calculations are based on the Golden Ratio - not a recursive function - so you can compute Fibonacci for large numbers without a stack overflow or timeout.
  
  
• Parameters

  Number n

  The number to find the Fibonacci number for. Inputs bigger than ~1470 is likely to produce Infinity.

• Return value The Fibonacci number of the input.
• Examples

  To find the Fibonacci number of 20

  // Output is 6765
  var n = Math.fibonacci(20);

• Resources See the Wikipedia entry at http://en.wikipedia.org/wiki/Fibonacci_number#Relation_to_the_Golden_Ratio for the relation between Fibonacci and the Golden Ratio.
• Download
  Download this function including dependencies
  Source

  Unless otherwise noted all code in the JSLab Standard Library is licensed as GPLv3. See http://www.gnu.org/licenses/gpl.html for the entire license.

  // ************************************************************************** // Copyright 2007 - 2009 Tavs Dokkedahl // Contact: http://www.jslab.dk/contact.php // // This file is part of the JSLab Standard Library (JSL) Program. // // JSL is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // any later version. // // JSL is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program. If not, see <http://www.gnu.org/licenses/>. // *************************************************************************** // Find the nth fibonacci number Math.fibonacci = function(n) { // Golden ratio var g = (1 + Math.sqrt(5)) / 2; return Math.round((Math.pow(g,n) - Math.pow(-g,-n)) / Math.sqrt(5)); };