Re: numeric precision when raising one numeric to another.

On 5/20/2005 2:26 PM, Tom Lane wrote:

> numeric_power can in theory deliver an exact answer when the exponent is
> a positive integer. Division can deliver an exact answer in some cases
> too --- but the spec doesn't say it must do so when possible. So I
> would say that there is no spec requirement for special behavior for
> integral exponents.

There are cases where a numeric_power could in theory deliver an exact
answer for a fractional exponent. That is when the exponent is a natural
fraction because the result is the m'th root of x^n (for n/m). As an
example 4^1.5 = 8. Of course does the m'th root need to produce a finite
result, which I think is not guaranteed for arbitrary numbers.

I'm not advocating to do that, just saying it is theoretically possible
for a subset of possible inputs.

Jan

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