 In the complex numbers there is already a canonical exponential function, the function that maps "x" to "e""x".In this setting the term exponential polynomial is often used to mean polynomials of the form "P"("x","e""x") where "P" ∈ C["x","y"] is a polynomial in two variables.There is nothing particularly special about C here, exponential polynomials may also refer to such a polynomial on any exponential field or exponential ring with its exponential function taking the place of "e""x" above.