A method and system for approximating functions, including a function approximation repository, which includes a hybrid lookup table configured to store coefficients associated with polynomials in factored form (PFFs), and a results store configured to store results. The system also includes a function approximation device that includes two processors, memory, an IO module and a function approximation module, which includes functionality to receive a request to approximate the function for an argument; verify that the argument falls within a function interval; perform a determination to find a subinterval in which the argument falls; select a PFF associated with the subinterval; obtain PFF coefficients associated with the PFF from the hybrid lookup table; evaluate the PFF using the PFF coefficients and the argument to obtain a result; store the result in the results store; and return the result as an answer to the requesting entity via the IO module.