I should've read more:
"Section 7.3 Division by zero", says 'For logB(0) when logBFormat is a
floating-point format, the sign of the infinity is minus (−∞).'
And I'm guessing this case matches it, because JVM and C standard lib too give
-Inf and nqp just maps the operations to VM's operations.
Looks like this bug re-appeared and Rakudo's function all come down to
nqp::log_n():
m: say log 0
rakudo-moar 2dd0dd: OUTPUT«-Inf»
m: use nqp; say nqp::log_n(0e0)
rakudo-moar 2dd0dd: OUTPUT«-Inf»
2008 IEEE 754[^1], in section 9.2, says log(0) needs to give a divideByZero
# New Ticket Created by Carl Mäsak
# Please include the string: [perl #60490]
# in the subject line of all future correspondence about this issue.
# URL: http://rt.perl.org/rt3/Ticket/Display.html?id=60490
Rakudo r32568:
$ ./perl6 -e 'my $result = log(0); say Still alive after getting
On Tue, Nov 11, 2008 at 11:57:02PM -0800, Carl Mäsak wrote:
Rakudo r32568:
$ ./perl6 -e 'my $result = log(0); say Still alive after getting $result'
Still alive after getting -inf
Now fixed in r32574:
$ ./parrot perl6.pbc -e 'my $result = log(0); say $result;'
Can't take log of 0
