Fibonacci Number Index
Compute the Fibonacci number index.
The Fibonacci number index is given by
where φ
is the golden ratio and F > 1
.
Usage
var fibonacciIndex = require( '@stdlib/math/base/special/fibonacci-index' );
fibonacciIndex( F )
Computes the Fibonacci number index for F_n > 1
.
var n = fibonacciIndex( 2 );
// returns 3
n = fibonacciIndex( 3 );
// returns 4
n = fibonacciIndex( 5 );
// returns 5
If provided either a non-integer or F_n <= 1
, the function returns NaN
.
var n = fibonacciIndex( -1 );
// returns NaN
n = fibonacciIndex( 3.14 );
// returns NaN
If provided NaN
, the function returns NaN
.
var n = fibonacciIndex( NaN );
// returns NaN
Examples
var fibonacciIndex = require( '@stdlib/math/base/special/fibonacci-index' );
var F1;
var F2;
var FN;
var n;
var i;
F1 = 1;
F2 = 1;
for ( i = 3; i < 79; i++ ) {
FN = F1 + F2;
F1 = F2;
F2 = FN;
n = fibonacciIndex( FN );
console.log( 'n(%d) = %d', FN, n );
}