The polynomial object is implemented in the previous chapter under the assumption that it is rather dense, that is, that most of its coeﬃcients, a0, a1, . . . , an, are nonzero, hence have to be stored. In this chapter, however, we are particularly interested in sparse polynomials, in which most of the coeﬃcients vanish, and only a few of them are nonzero. Thus, it makes no sense to store all of the coeﬃcients: it may save a lot of time and storage resources to ignore the zero coeﬃcients and store only the nonzero ones.