Re: Unexpected result using floor() function

On 03/14/2016 07:21 AM, Pujol Mathieu wrote:
> Hi
> I reproduce your bug using "PostgreSQL 9.3.6, compiled by Visual C++
> build 1600, 64-bit" on Windows 8
> I also notice that SELECT floor(4.725 * power(10, 2)::numeric + 0.5)
> work as expected

Seems to be related to the two forms of power():

http://www.postgresql.org/docs/9.4/interactive/functions-math.html

Function     Return Type
power(a dp, b dp)     dp
power(a numeric, b numeric)     numeric

So just doing:

test=> select floor(4.725 * power(10, 2.0) + 0.5);
  floor
-------
    473
(1 row)


works.

>
> Mathieu
>
> Le 14/03/2016 15:11, Frank Millman a écrit :
>> Hi all
>> I am running PostgreSQL 9.4.4 on Fedora 22.
>> SELECT floor(4.725 * 100 + 0.5) returns 473, which is what I expected.
>> SELECT floor(4.725 * power(10, 2) + 0.5) returns 472, which I find
>> surprising.
>> Please can someone explain the anomaly.
>> Thanks
>> Frank Millman
>
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> Mathieu PUJOL
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>


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