Maybe it makes sense that in the proposal below the parameter EXTRA_DIGITS could be SIGNIFICANT_DIGITS with a default value of 15 and maximum 18.
Its more 'documentable' and maybe easy to understand in general.
Pedro M. Ferreira wrote:
Yes. I think there are several options.
I checked the sprintf(ascii, "%A", num) output format and all the numbers that would fail because of DBL_DIG=15 are ok. After insertion on a table and conversion to double after a query, comparison a==b holds.
AFAICT "%A" is system independent.
I would (if I may) propose the following:
Have two parameters, say DOUBLE_OUTPUT and EXTRA_DIGITS. DOUBLE_OUTPUT would select from decimal output or normalized output. EXTRA_DIGITS would add the required extra digits, from 0 (default) to 3, when output is decimal.
EXTRA_DIGITS:
in the range [0:3]. 0 as defualt.
DOUBLE_OUTPUT:
'DECIMAL': sprintf(ascii, "%.*g", DBL_DIG+EXTRA_DIGITS, num); (default)
'NORMALIZED': sprintf(ascii, "%A", num);
The same could be done for floats (float4).
This way PG does not assume anything (DOUBLE_OUTPUT as 'NORMALIZED'), it does not hardwire 'inappropriate' assumptions about the number of significant digits in a double (default EXTRA_DIGITS=0), and it gives flexibility (EXTRA_DIGITS!=0) if needed.
I think this is functional and reasonable.
Regards,
Pedro M. Ferreira
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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 ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
