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Re: Bug #534: factorial function

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: lockhart(at)fourpalms(dot)org
Cc: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, j(dot)richter(at)wallstreet-develop(dot)de, pgsql-bugs(at)postgresql(dot)org
Subject: Re: Bug #534: factorial function
Date: 2001-12-10 16:37:44
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
Thomas Lockhart <lockhart(at)fourpalms(dot)org> writes:
>> ... I'd be sorely tempted to replace all three by a single
>> function that takes integer and returns numeric.

> Yikes. Although numeric is theoretically nice, it is hundreds of times
> slower than native doubles.

(a) As a wise man once said, "I can make it arbitrarily fast, if it
doesn't have to give the right answer".  (b) The factorial function
doesn't strike me as a performance bottleneck.  (c) I have no objection
to offering a double-precision-based gamma function alongside the
integer factorial function.  But I think factorial should give an exact
answer as far as is possible before it overflows.

			regards, tom lane

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