Multiply the ten largest integer scale prime numbers:
# select 2147483477::numeric * 2147483489::numeric * 2147483497::numeric * 2147483543::numeric * 2147483549::numeric * 2147483563::numeric * 2147483579::numeric * 2147483587::numeric * 2147483629::numeric * 2147483647::numeric;
?column?
------------------------------------------------------------------------------------------------
2085923946138988916149190605561960475118165298582929035878182900998428077414994652962618167119
(1 row)
Now, modulo this by any of the factors correctly returns 0:
# select '2085923946138988916149190605561960475118165298582929035878182900998428077414994652962618167119'::numeric% 2147483563;
?column?
----------
0
(1 row)
Also, diviing out all of the factors correctly returns 1:
# select 2085923946138988916149190605561960475118165298582929035878182900998428077414994652962618167119 / 2147483477 / 2147483489 / 2147483497 / 2147483543 / 2147483549 / 2147483563 / 2147483579 / 2147483587 / 2147483629 / 2147483647;
?column?
------------------------
1.00000000000000000000
(1 row)
This provides the solution to my problem: I merely needed to cast all of the numbers to numberic for product and modulo operations.
Thank you, Chadwick.
Bruno Wolff III wrote:
On Mon, Apr 26, 2004 at 10:18:52 -0400,
Chadwick Boggs <chadwickboggs@yahoo.com> wrote:
I need to perform modulo operations on extremely large numbers. The % operator is giving me number out of range errors and the mod(x, y) function simply seems to return the wrong results. Also, my numerator is in the format of a quoted string, which the mod function can't take.
I tried some large values and seem to be getting reasonable results. I did get some negative remainders, but I didn't find anything in the mod documentation on whether or not these were allowed. For small values I always got positive remainders so it isn't consistantly return the remainder closest to zero. My guess is that it has to do rounding when dividing numerics.
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