The platforms exhibiting the behavior have so far been MSVC Windows 10 64-bit
(both 32 and 64 bit processes), and Android x86. iOS 64-bit was not affected
and iOS 32-bit was not testable due to outside factors but my guess is that it
is not affected. macOS 64-bit was not affected.
I tried to come up with a simpler test case than the one I had but I was unsure
of how to trigger a path that entered 'codeReal'. For reference here was the
query that I was working with:
SELECT fl_result(prediction('EchoModel', dict_of('max_double',
1.7976931348623153e+308))) FROM kv_default AS _doc WHERE (_doc.flags & 1 = 0);
Between here and when dict_of was called, the value became a false infinity
(i.e. sqlite3_value_double returned inf). I couldn't reproduce this by just
selecting a literal from a query, which made me think it might be taking
another path. Since I couldn't figure out how to trigger it that way, I just
put in a call to strtod alongside the call to sqlite3AtoF inside of codeReal
and compared the results.
Jim Borden
On 2019/02/28 8:50, "[email protected] on behalf of Richard Hipp"
<[email protected] on behalf of [email protected]> wrote:
On 2/27/19, Jim Borden <[email protected]> wrote:
>
> My theory as to why this varies by platform is because of the use of long
> double during this calculation, which can vary in size. On the failing
> platforms they are the same size as regular double. This results in a
> rounding error of the "scale" portion of the calculation (via
sqlite3Pow10)
> which results in a false infinity.
Just out of curiosity, what platforms are you having trouble with. I
tried the script below on each of Linux (Ubuntu with gcc 5.4.0), Mac
(LLVM 10.0.0), and Win10 (MSVC) and got the answer you expect in all
three cases, namely 1.79769313486231522322e+308,
8.98846567431157611547e+307, Inf.
SELECT quote(1.7976931348623153E+308);
SELECT quote(1.7976931348623153E+308/2.0);
SELECT quote(1.7976931348623153E+308*2.0);
--
D. Richard Hipp
[email protected]
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