## Simple Polynomial

Subtype of MethodCorresponds to the SimplePolynomialFitting method in QuantLib.

The resulting discount factor

**for maturity**

*P(T)***depends on whether a constrain at 0 is imposed or not.**

*T*Without the constrain, it depends on

**parameters, where**

*N+1***is the degree of the polynomial and has the simple polynomial form:**

*N*

*P(T) = α(0)+α(1)T+α(2)T^2+...α(N)T^N ]*with parameter ordering:

*α(0), α(1), α(2), ..., α(N)*With the constrain, it depends on

**parameters as follows:**

*N*

*P(T) = 1+α(1)T+α(2)T^2+...α(N)T^N ]*with parameter ordering:

*α(1), α(2), ..., α(N)*This is a simple/crude, but fast and robust, means of fitting a yield curve