function fibonacciIndexf( F ) {
	return addon( F );
}
Computes the Fibonacci number index of a single-precision floating-point number.

@private
@param {NonNegativeInteger} F - Fibonacci number
@returns {NonNegativeInteger} Fibonacci number index

@example
var n = fibonacciIndexf( 0 );
// returns NaN

@example
var n = fibonacciIndexf( 1 );
// returns NaN

@example
var n = fibonacciIndexf( 2 );
// returns 3

@example
var n = fibonacciIndexf( 3 );
// returns 4

@example
var n = fibonacciIndexf( 5 );
// returns 5

@example
var n = fibonacciIndexf( 8 );
// returns 6

@example
var n = fibonacciIndexf( NaN );
// returns NaN

@example
var n = fibonacciIndexf( 3.14 );
// returns NaN

@example
var n = fibonacciIndexf( -1 );
// returns NaN