function logx( out, ax ) {
	var t2;
	var t1;
	var t;
	var w;
	var u;
	var v;

	t = ax - 1.0; // `t` has `20` trailing zeros
	w = t * t * polyvalW( t );
	u = INV_LN2_HI * t; // `INV_LN2_HI` has `21` significant bits
	v = ( t*INV_LN2_LO ) - ( w*INV_LN2 );
	t1 = u + v;
	t1 = setLowWord( t1, 0 );
	t2 = v - (t1 - u);

	out[ 0 ] = t1;
	out[ 1 ] = t2;
	return out;
}
Computes \\(\operatorname{log}(x)\\) assuming \\(|1-x|\\) is small and using the approximation \\(x - x^2/2 + x^3/3 - x^4/4\\).

@private
@param {Array} out - output array
@param {number} ax - absolute value of `x`
@returns {Array} output array containing a tuple comprised of high and low parts

@example
var t = logx( [ 0.0, 0.0 ], 9.0 ); // => [ t1, t2 ]
// returns [ -1265.7236328125, -0.0008163940840404393 ]