Hi all,
This is not really a SQLite issue, but the only solution I found out so far
consists in modifying SQLite sources.
Maybe someone here is able to clarify the following mystery...
---
SQLite shell output:
R:\>sqlite NUL "select 99990.1;"
99990.1
JSDB (www.jsdb.org) output:
js>var db = new SQLite();
js>db.exec("select 99990.1", function(r){writeln(r)});
99990.1=99990.1000000001
true
---
[Same rounding error with a couple of other "short" reals]
AFAIK, JSDB does use the SQLite library properly.
Technically, I can not figure out why sqlite3:sqlite3VXPrintf() behaves
differently if embedded in the SQLite shell or in JSDB.
In this particular case, "realvalue" values start to diverge slightly from the
"10.0" loop:
---
if( realvalue>0.0 ){
while( realvalue>=1e32 && exp<=350 ){ realvalue *= 1e-32; exp+=32; }
while( realvalue>=1e8 && exp<=350 ){ realvalue *= 1e-8; exp+=8; }
while( realvalue>=10.0 && exp<=350 ){ realvalue *= 0.1; exp++; } <--
while( realvalue<1e-8 ){ realvalue *= 1e8; exp-=8; }
while( realvalue<1.0 ){ realvalue *= 10.0; exp--; }
---
Adding intermediate exp power(s) of 2 (between 8 and 1) in the lines above does
fix the problem, e.g.:
(...)
if( realvalue>=1e4 && exp<=350 ){ realvalue *= 1e-4; exp+=4; }
(...)
However I still do not know why the same code/input/compiler options etc. lead
to slightly different results.
Any hint welcome!
Thanks in advance.
Regards,
Etienne
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