Function approximation includes receiving a number value to be input to a function. The number value includes a first and second plurality of bits. A first approximation value of a function is determined using the first plurality of bits as an index to a first lookup table including a plurality of candidate first approximation values. A first correction coefficient is determined using the first plurality of bits as an index to a second lookup table including a plurality of candidate first correction coefficients. A second correction coefficient is determined by using the first plurality of bits as an index to a third lookup table including a plurality of candidate second correction coefficients. A second approximation value of the function is determined based on the first approximation value, the first correction coefficient, and the second plurality of bits.