if (attribute == numerator) {
ArrayToken numeratorValue = (ArrayToken) numerator.getToken();
_numerator = numeratorValue.arrayValue();
} else if (attribute == denominator) {
ArrayToken denominatorValue = (ArrayToken) denominator.getToken();
_denominator = denominatorValue.arrayValue();
// Note: a<sub>0</sub> must always be 1.
// Issue a warning if it isn't.
if (!_denominator[0].isEqualTo(_denominator[0].one())
.booleanValue()) {