function frexp( x ) {
	var out = new Float64Array( 2 );
	addon( x, out );
	return out;
}
Splits a double-precision floating-point number into a normalized fraction and an integer power of two.

@private
@param {number} x - input value
@returns {Float64Array} output array

@example
var out = frexp( 4.0 );
// returns <Float64Array>[ 0.5, 3 ]

@example
var out = frexp( 0.0 );
// returns <Float64Array>[ 0.0, 0 ]

@example
var out = frexp( -0.0 );
// returns <Float64Array>[ -0.0, 0 ]

@example
var out = frexp( NaN );
// returns <Float64Array>[ NaN, 0 ]

@example
var out = frexp( Infinity );
// returns <Float64Array>[ Infinity , 0 ]

@example
var out = frexp( -Infinity );
// returns <Float64Array>[ -Infinity , 0 ]