1. A method comprising: providing an input signal range corresponding to a range of expected values for an input signal to a functional block; providing a minimum value error range corresponding to a range of error for a minimum value endpoint of the input signal range and a maximum value error range corresponding to a range of error for a maximum value endpoint of the input signal range; mapping the input signal range to one or more output signal ranges as a function of a range mapping function corresponding to the functional block; calculating a set of error extended input signal ranges by: adding a min endpoint of the minimum value error range to the minimum value of the input signal range; adding a max endpoint of the minimum value error range to the minimum value of the input signal range; adding the min endpoint of the maximum value error range to the maximum value of the input signal; and adding the max endpoint of the maximum value error range to the maximum value of the input signal range; mapping the set of error extended input signal ranges to a set of error extended output signal ranges as a function of the range mapping function; and calculating a minimum output error range and a maximum output error range as a function of a difference between the set of error extended output signal ranges and the output signal ranges.