do { BigRational factor = getFactor(i); BigDecimal xToThePower = powerIterator.getCurrentPower(); powerIterator.calculateNextPower(); step = factor.getNumerator().multiply(xToThePower, mathContext).divide(factor.getDenominator(), mathContext); xToThePower = powerIterator.getCurrentPower(); powerIterator.calculateNextPower(); factor = getFactor(i);