RBarryYoung (4/8/2010)

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Tom.Thomson (4/8/2010)

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RBarryYoung (4/7/2010)

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Paul White NZ (4/7/2010)

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RBarryYoung (4/7/2010)

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Yup, AFAIK SQRT, LOG and maybe POWER are the only things that return this error.

Ooo - I had never tried POWER. Have now, and you're right - though POWER (0, -1) gives me a divide-by-zero, rather than a domain error or invalid floating point operation.

Yeah, there's just so many reasons that ones wrong, it's hard to pick just one. Almost as bad as POWER(0, 0). 😀

:-DWhat do you want it to do?

Do you want it to

(a) return 0 so that f(x) = POWER (x,0) has a discontinuity at x = 0 while g(x) = POWER(0,x) is continuous everywhere (ie invert the current situation) or

(b) return NaN so that both functions are "undefined" at x=0 (but that requires support for the IEEE standard in SQLS, which hasn't yet happened: see http://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=239674) or

(c) return a domain error (so that both functions are "undefined" in such a way that no programmer can deal with it and must always test for the special case) or

(d) return two different catchable errors from POWER(0,X) (one for x < 0, another for x=0)

??

For me, (b) is the only useful approach, but note that this requires in addition a catchable error to handle attempts to insert NaNs into an index column (since such columns can allow NaN no more than they can allow NULL).

I seem to remember an argument made by one of my professors in college that "Zero to the Zeroth power" could be shown to be non-asymptotically discontinuous in an uncountably infinite number of ways and in fact in a transfinite-class number of ways that was at least one transfinite-class higher than that for "0/0". But that's probably too many exceptions to handle in most programs. 😀

Point being (I guess), that even plain old numerical mathematics theory can never be perfectly mapped/applied to real programming, there's always something that has to be swept under the carpet and just smoothed over for practical purposes. It's the main reason that I get so prickly when Relational Purists start moaning about NULLs in SQL. Heck if even basic arithmetic has to swallow DivideByZero in application, then I think that the Relational Model should be able to survive NULLs. But that's jsut me ... 😀