Re: numeric precision when raising one numeric to

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От Stephan Szabo
Тема Re: numeric precision when raising one numeric to
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Msg-id 20050520092144.Y84534@megazone.bigpanda.com
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Ответ на Re: numeric precision when raising one numeric to  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: numeric precision when raising one numeric to  ("Jim C. Nasby" <decibel@decibel.org>)
Re: numeric precision when raising one numeric to  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-general
On Fri, 20 May 2005, Tom Lane wrote:

> Has anyone bothered to actually look into the code?
>
> regression=# select power(2::numeric,1000);
>                                                                               power
>
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
10715086071862673209484250490600018105614048117055336074437503883703510511249361224931983788156958581275946729175531468251871452856923140435984577574698574803934567774824230985421074605062371141877954182153046474983581941267398767559165543946077062914571196477686542167660429831652624386837205668069376.0000000000000000
> (1 row)
>
> AFAICT the only thing missing is a pg_operator entry linked to the
> function.

It appears fairly limited however given that you rapidly run into the
numeric maximum length for exp.

It also doesn't seem to work terribly well:

sszabo=# select power(0.1::numeric, 15);
       power
--------------------
 0.0000000000000010
(1 row)

sszabo=# select power(0.1::numeric, 16);
       power
--------------------
 0.0000000000000001
(1 row)

sszabo=# select power(0.1::numeric, 17);
       power
--------------------
 0.0000000000000000
(1 row)

sszabo=# select power(0.1::numeric, 17)*100;
      ?column?
--------------------
 0.0000000000000000
(1 row)


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