 Because formula_46 is a polynomial of degree , we have

where is a polynomial of degree formula_48.Since is orthogonal to formula_32 we have

We can then write

The term in the brackets is a polynomial of degree formula_48, which is therefore orthogonal to formula_32.The integral can thus be written as

According to equation (), the weights are obtained by dividing this by formula_55 and that yields the expression in equation ().