Re: float output precision questions

I sent an email before receiving the one below. I am happier also with 
the extra_digits way (from the previous email I thought the options were 
DBL_DIG or DBL_DIG+2).

> I'm not happy with adding the hex-output option, since it's not
> very portable and doesn't seem necessary to solve the problem anyway.

Agree.

> Perhaps something like
> 
> extra_float_digits    int    range -2 to 2, default 0
> 
> extra_float_digits adjusts the number of digits displayed for float4 and
> float8 output; the base value of 0 means we output FLT_DIG or DBL_DIG
> digits respectively.

Agree.

> 
> Per discussion, there's no reason to allow a value greater than 2, but
> I'm not as sure what the lower limit should be --- maybe there's some
> use in setting it less than -2?

I could see some use. At least in my type of application. When people 
are shure they only need p significant digits, they can set 
extra_float_digits to an apropriate negative value and spare a lot in 
storage for dumps and backups. In this case it would make sense to let
extra_float_digits go to -13.

Regards,
Pedro
> 
>             regards, tom lane
> 
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-- 
----------------------------------------------------------------------
Pedro Miguel Frazao Fernandes Ferreira
Universidade do Algarve
Faculdade de Ciencias e Tecnologia
Campus de Gambelas
8000-117 Faro
Portugal
Tel./Fax:  (+351) 289 800950 / 289 819403
http://w3.ualg.pt/~pfrazao