implementation

evaluation

first we need to transform from [1,1] to [𝑎,𝑏] which required to update points and weights

𝑥𝑖=𝑏𝑎2𝜉𝑖+𝑎+𝑏2

where 𝑥𝑖 is the new mapped point and 𝜉𝑖 is the old one

𝑤𝑖=𝑏𝑎2𝑤𝑖 𝐼=𝑏𝑎𝑓𝑑𝑥=𝑏𝑎2𝑤𝑖𝑓(𝑥𝑖)

exact for 𝑛 node

up to 2𝑛1 degree