function lucasf( n ) {
	if (
		isnanf( n ) ||
		isIntegerf( n ) === false ||
		n < 0 ||
		n > MAX_LUCAS
	) {
		return NaN;
	}
	return LUCAS[ n ];
}
Computes the nth Lucas number as a single-precision floating-point number.

@param {NonNegativeInteger} n - the Lucas number to compute
@returns {NonNegativeInteger} Lucas number

@example
var y = lucasf( 0 );
// returns 2

@example
var y = lucasf( 1 );
// returns 1

@example
var y = lucasf( 2 );
// returns 3

@example
var y = lucasf( 3 );
// returns 4

@example
var y = lucasf( 4 );
// returns 7

@example
var y = lucasf( 5 );
// returns 11

@example
var y = lucasf( 6 );
// returns 18

@example
var y = lucasf( NaN );
// returns NaN

@example
var y = lucasf( 3.14 );
// returns NaN

@example
var y = lucasf( -1.0 );
// returns NaN