in reply to using callback function

You need to include the & when you take the reference (otherwise your calling h and then taking a reference to teh result):

j (\@ar, \@vr, \&h);

And for most ordinary uses you can drop the & when calling the function as above. To invoke the coderef I prefer to use ->:

$k->($i,$j);

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
"Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon