public override string ToString() { var result = "y = " + Slope.ToInvariantString() + "x"; if (YIntercept.IsApproximately(0)) { return(result); } if (YIntercept < 0) { result += " - " + (-YIntercept).ToInvariantString(); } else { result += " + " + YIntercept.ToInvariantString(); } return(result); }