Re: Patch for DateTime::Format::W3CDTF to respekt second fragment part
Jonathan Leffler wrote: Or, what happens if there are 10 digits after the decimal point. That's what the substr() is for. Yeah, mostly academic, except I'm working towards a time type (not for Perl per se) that extends down to picoseconds (and up to 10^12 years, too). At least 105 bits, then. TAI64 covers nearly 10^12 years, of course, and the extension TAI64NA goes down to attoseconds in a 128-bit format. What's the concept behind your type? Personally I like to use bignum rational arithmetic, for unlimited resolution. Performance is atrocious with the Perl bignum libraries, unfortunately. -zefram
Re: Patch for DateTime::Format::W3CDTF to respekt second fragment part
Zefram [EMAIL PROTECTED] wrote:
Re: Patch for DateTime::Format::W3CDTF to respekt second fragment part
Julian Haupt wrote:
+if ($date =~ s/\.(\d+)$// )
+{
+ my $fraction = $1;
+ $p{'nanosecond'} = (1 / $fraction) * 10**9;
+}
That inversion can't be right. Surely you mathematically want
$p{'nanosecond'} = 0.$fraction * 10**9;
but actually the nanoseconds member is supposed to be an integer, and
it would be better to avoid floating-point arithmetic entirely:
$fraction = substr($fraction, 0, 9);
$fraction .= 0 x (9 - length($fraction);
$p{'nanosecond'} = 0 + $fraction;
Beware the picosecond!
Or, what happens if there are 10 digits after the decimal point. I've no
idea what -3 zeroes looks like, but the answer is unlikely to be correct.
Yeah, mostly academic, except I'm working towards a time type (not for
Perl per se) that extends down to picoseconds (and up to 10^12 years,
too).
--
Jonathan Leffler ([EMAIL PROTECTED])
STSM, Informix Database Engineering, IBM Information Management Division
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Re: Patch for DateTime::Format::W3CDTF to respekt second fragment part
Julian Haupt wrote:
+if ($date =~ s/\.(\d+)$// )
+{
+ my $fraction = $1;
+ $p{'nanosecond'} = (1 / $fraction) * 10**9;
+}
That inversion can't be right. Surely you mathematically want
$p{'nanosecond'} = 0.$fraction * 10**9;
but actually the nanoseconds member is supposed to be an integer, and
it would be better to avoid floating-point arithmetic entirely:
$fraction = substr($fraction, 0, 9);
$fraction .= 0 x (9 - length($fraction);
$p{'nanosecond'} = 0 + $fraction;
-zefram
