function erfcx( x ) {
	return addon( x );
}
Evaluates the scaled complementary error function.

@private
@param {number} x - input value
@returns {number} evaluated scaled complementary error function

@example
var y = erfcx( 0.0 );
// returns 1.0

@example
var y = erfcx( 1.0 );
// returns ~0.4276

@example
var y = erfcx( -1.0 );
// returns ~5.01

@example
var y = erfcx( 50.0 );
// returns ~0.011

@example
var y = erfcx( -50.0 );
// returns +Infinity

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