DEVICE AND METHOD FOR COMPUTING A FUNCTION VALUE OF A FUNCTION

A device is provided for computing a function value of a function F. The device includes a memory, a truncator unit, a selector unit, and an evaluator unit. The memory contains a look-up table comprising a set of entries, each entry having associated with it a domain and an approximation function for approximating F on the associated domain. The truncator unit is arranged to truncate or round a first value X1 to generate a second value X2. The selector unit is arranged to select an entry of the lookup-table according to the second value X2, thus selecting the approximation function that is associated with the selected entry. The evaluator unit is arranged to determine the function value of the selected approximation function at the first value X1.