public String toComplexString() {
	if(this.b>=0)
	    return String.format("%.3f +%.3fi", this.a+this.b*Math.cos(ALPHA), this.b*Math.sin(ALPHA));
	else
	    return String.format("%.3f %.3fi", this.a+this.b*Math.cos(ALPHA), this.b*Math.sin(ALPHA));
    }