bigint vs. bignum

[Alex]

Hello, I'm new to Perl

I have a small program, which uses only (big) integers, but works
differently with "use bigint" and "use bignum". Can you please explain
why?

sub Next($)
{
my $var = shift;
my $tst = $var % 2;
return ($tst == 0) ? $var / 2 : $var * 3 + 1;
}

my $n = 2 ** 1000 - 1;
my $counter = 0;

while (1)
{
$n = Next($n);
if ($n == 1)
{
print("counter = ", $counter, "\n");
last;
}
$counter++;
}

Thank you in advance
Alex

 

[xhoster]

Hello, I'm new to Perl

I have a small program, which uses only (big) integers, but works
differently with "use bigint" and "use bignum". Can you please explain
why?

sub Next($)
{
my $var = shift;
my $tst = $var % 2;
return ($tst == 0) ? $var / 2 : $var * 3 + 1;

use bignum turns on upgrading.

When the division by 2 happens, the BigInt upgrades to BigFloat. It
doesn't look to see if the division results in an integer before
upgrading--it just does it.

Xho

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