foreach (@hlines) 
#each line from file1 was saved to this array.
{
$xh= substr $_,31,8;
$yh= substr $_,40,8;
$zh= substr $_,48,8;
		
foreach $pline (@plines)
#ditto, each line from file2 saved to this array
{
$x1= substr $pline,31,8; #using $_ here instead of $pline aborts execution due to compile errors.
$y1= substr $pline,40,8;
$z1= substr $pline,48,8;
	                        
$r2=((&square($xh-$x1))+(&square($yh-$y1))+(&square($zh-$z1)));
$r=sqrt($r2);
print "$i. $r2 and square root is $r\n";
}
}