* @param other subtrahend.
* @return new instance of {@code Decimal} which value is {@code this.value} - {@code other.value}.
*/
public Decimal sub(final Decimal other) {
Real result = new Real(this.value);
result.sub(other.value);
return new Decimal(result);
}
/**
* Calculates square of {@code this.value} according to {@link ral.Real#sqr()}.