Re: BUG #5428: Discrepency in remainder on mod function. - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #5428: Discrepency in remainder on mod function.
Date
Msg-id 15461.1271452285@sss.pgh.pa.us
Whole thread Raw
In response to BUG #5428: Discrepency in remainder on mod function.  ("Khee Chin" <kheechin@gmail.com>)
Responses Re: BUG #5428: Discrepency in remainder on mod function.  (Khee Chin <kheechin@gmail.com>)
List pgsql-bugs
"Khee Chin" <kheechin@gmail.com> writes:
> I'm not certain if this is a bug or an intended behavior.

> I noticed a discrepency in calculating the remainders across pgsql (PG),
> wolframalpha (W) and using Knuth's description of floored division

We follow whatever the C compiler's idea of modulo is.  This is somewhat
standardized, in fact, and I'm not excited about changing it.
Especially not by introducing roundoff-prone double arithmetic into what
had been an exact operation.

            regards, tom lane

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