On Thu Feb 15 08:02:38 2007, gak-a@web.de wrote:
Show quoted text> When I use Math:BigInt, the following perl code results in an error:
>
> sub log2{
> my $n = shift;
> return log($n)/log(2);
> }
>
> Error: "Can't use an undefined value as an ARRAY reference at
> /usr/lib/perl5/5.8.8/Math/BigInt/Calc.pm line 1338."
>
> The same error also shows up if I use the Math::Complex logn function
> instead.
>
> I use Perl version: v5.8.8 on a GNU/Linux system.
>
I have fixed this bug and it will be in Math::BigInt v1.80.
However, some notes:
under "use Math::BigInt;", log(2) will be a plain Perl scalar, unless
you use "bignum".
log(Math::BigInt->new(288)) will result in a BigInt, e.g. a truncated
result
log(Math::BigInt->new(288))/log(2) will result in inf, since log(2) is
about 0.6, and this is, when converted into a BigInt, simple truncated 0.
If you want to calcuate big logarithms, then you need to use Math::BigFloat:
te@linux:~/perl/math/Math-BigInt-1.80> perl -Ilib log.pl
Inside log2: 5.66296048013595 0.693147180559945
8.16992500144231
Inside log2: 5 0.693147180559945
inf
Inside log2: 5.662960480135945929876651081135934249672 0.693147180559945
8.16992500144231600991874978552459796636
te@linux:~/perl/math/Math-BigInt-1.80> cat log.pl
use Math::BigInt;
use Math::BigFloat;
print log2(288), "\n";
print log2(Math::BigInt->new(288)), "\n";
print log2(Math::BigFloat->new(288)), "\n";
sub log2{
my $n = shift;
print "Inside log2: ", log($n), " ", log(2), "\n";
return log($n) / log(2);
}
Thank you for your report!
