While explaining the uses of the general pow(xx, yy) Michel Hack said:
> I do see an issue however in the case where yy is a singleton, because
> that is now an exponent with an even denominator (in both decimal and
> binary) if it has a non-zero fractional part. Dan's reasoning does not
> apply to this case, and it would be necessary to raise "Undefined" if xx
> contains negative points.
Decimal is not similar to binary in this respect. For decimal, if yy is a singleton of the value 0.12 for example then it has indeed an odd denominator since 0.12=12/100 = 3/25. The result in this case may be easily defined for xx with negative points.
Since ten is a composite number, there are many cases where the fraction given by a decimal significand reduces to one with an odd denominator. The condition for that is that the numerator has enough powers of two to eliminate the powers of two in the denominator.
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Hossam A. H. Fahmy
Assistant Professor
Electronics and Communications Department
Cairo University
Egypt