function asinh( x ) {
	return addon( x );
}
Computes the hyperbolic arcsine of a double-precision floating-point number.

@private
@param {number} x - input value
@returns {number} hyperbolic arcsine

@example
var v = asinh( 0.0 );
// returns 0.0

@example
var v = asinh( 2.0 );
// returns ~1.444

@example
var v = asinh( -2.0 );
// returns ~-1.444

@example
var v = asinh( NaN );
// returns NaN