Thank you Pawan for the Links. They solved my problem.
I am new to both Linux and Perl. As far as I can make out, whereas BigInt is transparent in Perl, BigFloat is notat least not yet. A scalar variable has to be changed explicitly to a BigFlaot variable before it can be used as such. The following code gives the division of 1/3 as 500 3s to the right of the decimal point (please note this is a beginner's program):

#!/usr/bin/perl5.8.8 w #path to perl in my system

#gives division $nom/$denom (1/3) to $prec (500) precise digits

#to the right of the decimal point.

use strict;


use Math::BigInt;

use Math::BigFloat;

my $nom = 1;

my $denom = 3;

my $x = Math::BigFloat>new($nom); # scalar $nom > BigFloat $x.

my $prec = 500;

Math::BigFloat>precision($prec); # sets precision

my $value = $x>copy()>bdiv($denom); # BigFloat division $x/$denom

print $value,"\n";

Problem solved, thank you!
zakad