A computer-implemented 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 an output signal range 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; wherein calculating a set of error extended input signal ranges includes calculating permutations of the min and max endpoints of the minimum value error range added to the minimum value of the input signal range and the min and max endpoints of the maximum value error range added 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, wherein the minimum output error range is a range of signal value error corresponding to the minimum value in the range of the output signal, and a maximum output error range, wherein the maximum output error range is a range of signal value error corresponding to the maximum value in the range of the output signal, as a function of a difference between the set of error extended output signal ranges and the output signal range. 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 an output signal range 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; wherein calculating a set of error extended input signal ranges includes calculating permutations of the min and max endpoints of the minimum value error range added to the minimum value of the input signal range and the min and max endpoints of the maximum value error range added to the maximum value of the input signal range; 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; wherein calculating a set of error extended input signal ranges includes calculating permutations of the min and max endpoints of the minimum value error range added to the minimum value of the input signal range and the min and max endpoints of the maximum value error range added 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, wherein the minimum output error range is a range of signal value error corresponding to the minimum value in the range of the output signal, and a maximum output error range, wherein the maximum output error range is a range of signal value error corresponding to the maximum value in the range of the output signal, as a function of a difference between the set of error extended output signal ranges and the output signal range.