Hi Tom,
Sorry. After sending to group one friend of mine explained to me how round works -- not postgresql round, but round in math.
I do not know any software that would produce that output.
I thought that when 1.8947 was rounded to 2 decimal places, 7 would round-up 4, then "5" would round-up 9.
Reading
http://www.ai.com.br/pessoal/indices/2A1A.HTM show the correct way (sorry, the page is in brazilian portuguese).
Anyway, the document shows: DO NOT DO RECURSIVE ROUNDS! hehe.
Thanks for the answer and sorry for the incorrect question.
Regards,
Fernando Pinheiro
2007/7/11, Tom Lane < tgl@sss.pgh.pa.us>:"Fernando Madruga Pinheiro" < fernando.madrugapinheiro@gmail.com> writes:
> If I use ROUND(1.8947, 2), it should return 1.90, but it does return 1.89.
Why do you consider that wrong? It's the closest approximation.
Do you know of any other software that would produce 1.90 from a
similar query?
> Rounding to 3 decimal places, then 2 (eg.: ROUND(ROUND(1.8947, 3), 2) ) then
> I get 1.90!
Since ROUND() is a lossy process by definition, you cannot expect
that different multi-step paths will always yield the same result.
regards, tom lane