本人坚信、并一再重申，任何有意义的讨论，必须有明确的议题，所涉概念，必须要有公认的定义，不可自创。

基于此，我重复一遍本人的观点：美国目前市面通行的房贷，除去月付款小于利息的 negative mortgage，履约付款，利息结算均为单利。

本人的立场依据已于好几个帖子中说明。不赘。此处仅引用并复习一哈复利的定义： 

"Compound interest arises when interest is added to the principal, so that, from that moment on, the interest that has been added also earns interest. This addition of interest to the principal is called compounding. " （Source: http://en.wikipedia.org/wiki/Compound_interest）

该文并特意说明：

"U.S. mortgages use an amortizing loan, not compound interest. With these loans, an amortization schedule is used to determine how to apply payments toward principal and interest. Interest generated on these loans is not added to the principal, but rather is paid off monthly as the payments are applied."

我认为以上定义灰强准确。

刚才见有同学罗列一大堆坚持房贷是复利的五味大师级别的同学，以示房贷复利派的观点正确。给我留下灰强深刻的印象。

请允许我也介绍一位大师。关于美国房贷是单利还是复利，这位大师认为：

"There are two kinds of mortgages in the US. One accrues interest monthly, and is simple interest except when it allows negative amortization, when it is compound interest. This mortgage has no special name because most mortgages are of this type... The second kind of mortgage accrues interest daily and is always simple interest. This kind of mortgage ought to be called a "daily accrual mortgage" because that would clearly distinguish it from the standard mortgage." (http://www.washingtonpost.com/wp-dyn/content/article/2008/01/25/AR2008012501739.html)

这位大师的名字是 Jack M. Guttentag, now Professor of Finance Emeritus, formerly Jacob Safra Professor of International Banking, at the Wharton School of the University of Pennsylvania. Earlier he was Chief of the Domestic Research Division of the Federal Reserve Bank of New York, on the senior staff of the National Bureau of Economic Research, and managing editor of both the Journal of Finance (1974-77) and the Housing Finance Review (1983-89). （http://www.inman.com/buyers-sellers/columnists/jack-guttentag）

我们五味土产的大师大部分是我的朋友，学问精深博大，想象力极其轰乎，我一向敬仰。但是，在房贷单利还是复利的问题上，如果非要选择相信谁的话，我选择急克大师，in a heart beat。

喔，再补充一句：单利不是零利息，不是免费的午餐，银行也没有施舍行善。

谢谢。