A posynomial, also known as a posinomial in some literature, is a function of the form A posynomial, also known as a posinomial in some literature, is a function of the form where all the coordinates x i {displaystyle x_{i}} and coefficients c k {displaystyle c_{k}} are positive real numbers, and the exponents a i k {displaystyle a_{ik}} are real numbers. Posynomials are closed under addition, multiplication, and nonnegative scaling.