Agarwal, Sumit; Driscoll, John D.; Laibson, David I. - Department of Economics, Harvard University - 2012
We derive the ï¬rst closed-form optimal reï¬nancing rule: Reï¬nance when the current mortgage interest rate falls below the original rate by at least \(\frac{1}{ψ}\)[φ + W (− exp (−φ))]. In this formula W(.) is the Lambert W-function, ψ = \(\frac{2 (Ï +...