function cadd( z1, z2 ) {
	var v = addon( z1, z2 );
	return new Complex128( v.re, v.im );
}
Adds two double-precision complex floating-point numbers.

@private
@param {Complex128} z1 - complex number
@param {Complex128} z2 - complex number
@returns {Complex128} result

@example
var Complex128 = require( '@stdlib/complex/float64/ctor' );

var z = new Complex128( 5.0, 3.0 );

var out = cadd( z, z );
// returns <Complex128>[ 10.0, 6.0 ]